ACCEPT
                                                                 
                                                                SANITIZATION OF CONTENT NEGOTIATION HEADERS SUCH AS ACCEPT-LANGUAGE. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    ACCOUNTING
                                                                 
                                                                FOR COLLECTING METRICS PER TENANT, CONTENT TYPE AND MORE, FOR USE IN DASHBOARDS AND MONITORING 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    ACLPLUS
                                                                 
                                                                MORE FLEXIBLE IP ADDRESS MATCHING, FOR EXAMPLE USING IP ADDRESSES STORED IN KVSTORE. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    ACTIVEDNS
                                                                 
                                                                A LIBADNS VCL INTERFACE FOR CREATING DNS_GROUPS AND SETTING UP DYNAMIC BACKENDS 
                                                             
                                                        
                                                     | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    BLOB
                                                                 
                                                                THIS VMOD PROVIDES UTILITY FUNCTIONS AND AN OBJECT FOR THE VCL DATA TYPE BLOB, WHICH MAY CONTAIN ARBITRARY DATA OF ANY LENGTH. 
                                                             
                                                        
                                                     | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    BODYACCESS
                                                                 
                                                                THIS VMOD GIVES VCL SOME ACCESS TO THE REQUESTBODY. A COMMON USE CASE IS TO ALLOW CACHING OF POST REQUESTS, WHERE THE REQUEST BODY NEEDS TO BE PART OF THE HASH. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    BROTLI
                                                                 
                                                                ADDS END-TO-END SUPPORT FOR BROTLI LOSSLESS COMPRESSION ALGORITHM 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                             
                                                         | 
                                                        
                                                             
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    COOKIEPLUS
                                                                 
                                                                ADVANCED COOKIE MANIPULATION AND FILTERING CAPABILITY, FOR BOTH REQUEST AND RESPONSE COOKIES. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    COOKIE
                                                                 
                                                                COOKIE MANIPULATION IN VCL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    CRYPTO
                                                                 
                                                                CRYPTOGRAPHIC FUNCTIONALITY TO ENCRYPT DATA AT REST IN THE CACHE, HEADERS AND BODY. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    CURL
                                                                 
                                                                HTTP COMMUNICATION FROM VCL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    DIGEST
                                                                 
                                                                VARNISH MODULE (VMOD) FOR COMPUTING HMAC, MESSAGE DIGESTS AND WORKING WITH BASE64. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    DIRECTORS
                                                                 
                                                                LOAD BALANCING BETWEEN BACKENDS BASED ON ROUND ROBIN, FALLBACK, RANDOM, HASH AND SHARDING. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    EDGESTASH
                                                                 
                                                                REALTIME TEMPLATING ENGINE BASED ON MUSTACHE, THAT ALLOWS JSON TO BE COMPOSED INTO RESPONSES. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    FILE
                                                                 
                                                                FILE SYSTEM OPERATIONS ALLOWING VARNISH TO ACT AS A FILE SERVER AS WELL AS INTERACTING WITH THE FILE SYSTEM FROM VCL. CRUD OPERATIONS ON FILES, AND EXECUTING COMMANDS – ALL FROM VCL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    FORMAT
                                                                 
                                                                BRINGS FORMATTED STRINGS TO VCL FOR EASIER STRING BUILDING 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    GEOIP
                                                                 
                                                                THIS VARNISH MODULE EXPORTS FUNCTIONS TO LOOK UP GEOIP COUNTRY CODES FROM THE MAXMIND DATABASE. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    GOTO
                                                                 
                                                                DYNAMIC BACKENDS BASED ON DNS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    HEADER
                                                                 
                                                                VARNISH MODULE FOR MANIPULATION OF DUPLICATED HTTP HEADERS, FOR INSTANCE MULTIPLE SET-COOKIE HEADERS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    HTTP
                                                                 
                                                                ADVANCED HTTP COMMUNICATION FROM VCL. THIS INCLUDES ASYNCHRONOUS AND SYNCHRONOUS CALLS, PRE-FETCH CAPABILITIES, REQUEST MIRRORING – ALL WITH CONNECTION POOLING. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    IMAGE
                                                                 
                                                                COMPRESS JPEGS AND PNGS INTO WEBP FORMAT AND STORE A COMPRESSED COPY IN THE CACHE. OPTIONALLY SCALE, RESIZE OR CHANGE THE QUALITY OF CONVERSION. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    JSON
                                                                 
                                                                PARSE JSON STRINGS FROM HEADERS OR BODY AND READ THE VALUE FOR SPECIFIC KEYS IN VCL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    JWT
                                                                 
                                                                MAKES IT PRACTICAL TO MANIPULATE JSON WEB TOKENS IN VCL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    KVSTORE
                                                                 
                                                                HIGH PERFORMANCE INTERNAL KEY VALUE STORE ACCESSIBLE FROM VCL, WITH OPTIONAL TTLS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    LEASTCONN
                                                                 
                                                                BACKEND LOAD BALANCING BY THE NUMBER OF CONNECTIONS. TRAFFIC WILL BE DIRECTED TO THE BACKEND WITH THE LEAST NUMBER OF ACTIVE CONNECTIONS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    MEMCACHED
                                                                 
                                                                VARNISH MODULE TO ACCESS AND INTERACT WITH MEMCACHED SERVERS FROM VCL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    PAYWALL
                                                                 
                                                                VMOD TO PROVIDE HELPER FUNCTIONALITY THAT IS USEFUL WHEN BUILDING A VCL BASED PAYWALL. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    PROBE-PROXY
                                                                 
                                                                ADDS FLEXIBILITY TO REDIRECT PROBES AND TREAT THEM AS HTTP REQUESTS IN ORDER TO ROUTE, CACHE AND COLLAPSE THEM 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    PROXY
                                                                 
                                                                EXPOSES PROXY-PROTOCOL-V2 TLV ATTRIBUTES IF A CONNECTION WAS MADE USING THE PROXY PROTOCOL. CAN BE USED TO RETRIEVE TLS-RELATED INFORMATION. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    PURGE
                                                                 
                                                                PROVIDES A FINER-GRAINED CONTROL THAN REGULAR PURGING, SUCH AS SOFT PURGE. IT ALSO RETURNS THE NUMBER OF PURGED OBJECTS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    RESOLVER
                                                                 
                                                                 ENABLES REVERSE IP DNS RESOLUTION AND VERIFICATION, AND VERIBOT LIBRARY FOR DOMAIN-BASED ACCESS CONTROLS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    REWRITE
                                                                 
                                                                AN EFFICIENT WAY TO DO REWRITES BASED ON RULES IN A SEPARATE RULES FILE. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    RTSTATUS
                                                                 
                                                                THIS VMOD WILL EXPOSE VARNISHSTAT COUNTERS AND BACKEND INFORMATION OVER HTTP, WHICH MAKES IT POSSIBLE TO GET THIS DATA BY SENDING AN HTTP REQUEST TO VARNISH. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    S3
                                                                 
                                                                Functionality for using Varnish in front of S3, including a dynamic backend director for S3 bucket endpoints 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    SAINTMODE
                                                                 
                                                                SAINTMODE LETS YOU DEAL WITH A BACKEND THAT IS FAILING IN RANDOM WAYS FOR SPECIFIC REQUESTS. IT MAINTAINS A BLACKLIST PER BACKEND, MARKING THE BACKEND AS SICK FOR SPECIFIC OBJECTS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    SESSION
                                                                 
                                                                MODIFICATION OF VARIABLES ON A PER SESSION BASIS. FOR NOW ONLY IDLE TIMEOUT CAN BE MODIFIED. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    SLICER
                                                                 
                                                                CACHE PARTIAL RESPONSES BY ISSUING A RANGE REQUEST TO THE BACKEND, BASED ON THE CLIENT’S RANGE HEADER. 
                                                             
                                                        
                                                     | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    STALE
                                                                 
                                                                A WAY TO DO STALE-WHILE-REVALIDATE AND STALE-ON-ERROR WITHOUT RESTARTING, TO INCREASE THE LIFETIME OF STALE OBJECTS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    STD
                                                                 
                                                                 CONTAINS BASIC FUNCTIONS SUCH AS TIME AND DURATION FUNCTIONS, QUERY SORTING AND VARIOUS CAST FUNCTIONALITY. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    SYNTHBACKEND
                                                                 
                                                                CREATING SYNTHETIC BACKENDS THAT CAN BE USED FOR CACHE WARMING OR PUSHING OBJECTS INTO CACHE. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    TCP
                                                                 
                                                                WHEN RUNNING ON SYSTEMS WITH THE NECESSARY KERNEL SUPPORT, THIS VMOD LETS VARNISH ARTIFICIALLY SLOW DOWN SENDING OF RESPONSE BODIES TO REQUESTING CLIENTS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    UDO
                                                                 
                                                                IMPROVED, MORE DYNAMIC LOAD BALANCING LOGIC 
                                                             
                                                        
                                                     | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    UNIX
                                                                 
                                                                MAKING INFORMATION ABOUT THE PEER PROCESS AVAILABLE IN VCL (USER, GROUP, UID AND GID). 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    URI
                                                                 
                                                                MAKES IT EASIER TO PARSE, MANIPULATE AND REWRITE FULL URIS 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    URLPLUS
                                                                 
                                                                 ADVANCED URL MANIPULATION AND FILTERING CAPABILITY, FOR BOTH QUERY PARAMETERS AND THE PATH. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    VAR
                                                                 
                                                                THIS VMOD IMPLEMENTS VARIABLE SUPPORT IN VCL. IT SUPPORTS STRINGS, INTEGERS AND REAL NUMBERS. THERE ARE METHODS TO GET AND SET EACH DATA TYPE. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    VHA
                                                                 
                                                                HELPER VMOD TO SUPPORT CACHE REPLICATION FUNCTIONALITY. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    VSTHROTTLE
                                                                 
                                                                RATE LIMITING IN VCL BASED ON THE TOKEN BUCKET ALGORITHM. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    VTC
                                                                 
                                                                PROVIDES A WAY TO TRIGGER CORNER CASES FOR VTC TESTS THAT CAN BE RUN VIA VARNISHTEST. 
                                                             
                                                        
                                                     | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    XBODY
                                                                 
                                                                ENABLES MODIFICATION AND EXTRACTION OF CONTENT IN REQUEST AND RESPONSE BODIES USING REGULAR EXPRESSIONS. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    XKEY
                                                                 
                                                                CACHE INVALIDATION BASED ON SURROGATE CACHE KEYS IN VARNISH. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                
                                                
                                                    
                                                        
                                                            
                                                                
                                                                    YKEY
                                                                 
                                                                RESOURCE OPTIMIZED CACHE INVALIDATION BASED ON SURROGATE CACHE KEYS IN VARNISH, MORE RESOURCE EFFICIENT THAN XKEY. 
                                                             
                                                        
                                                     | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         | 
                                                        
                                                            X
                                                         |