IRML: A Rule Specification Language for Intermediary Services
From: http://www.ietf-opes.org/documents/draft-beck-opes-irml-00.txt
See:  IETF Working Group for Open Pluggable Edge Services (OPES)
      http://xml.coverpages.org/opes.html

Appendix - IRML DTD and examples

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   <!ELEMENT rulemodule    (owner, protocol, rule+)>  
   <!ELEMENT owner         (name, id)>  
   <!ELEMENT name          (#PCDATA)>  
   <!ELEMENT id            (#PCDATA)>  
   <!ELEMENT protocol      (#PCDATA)>  
   <!ELEMENT rule          (property | action)+>  
   <!ELEMENT property      (property | action)+>  
   <!ELEMENT action        (#PCDATA)>  
   <!ATTLIST owner         class  (content provider |   
                                   access provider | client) #REQUIRED>  
   <!ATTLIST rule          processing-point   (1|2|3|4)      #REQUIRED>  
    
   <!ATTLIST property      name               CDATA          #REQUIRED>  
   <!ATTLIST property      matches            CDATA          #REQUIRED>  
   <!ATTLIST property      case-sensitive     (yes|no)   #DEFAULT "no">  
     
Appendix - Rule Module Examples  
    
     
   Content Provider Rule Module Example for Advertisement Insertion  
   Service  
     
   <?xml version="1.0"?>  
   <rulemodule>  
     <owner class="content provider">  
       <name>Lucent Technologies</name>  
       <id>www.lucent.com</id>  
     </owner>  
     <protocol>http</protocol>  
     <rule processing-point="4">  
       <!- Is the requested Web document the home page? -->  
       <property name="Request-Path" matches="^/$|^/index.html$" 
       case-sensitive="yes">  
          <!-Does the user send us a cookie for user identification?-->  
          <property name="Cookie" matches="UserID=">  
             <action>icap://adserver.net/insertad</action>  
          </property>  
       </property>  
     <rule>  
   </rulemodule>  
     
   Access Provider Rule Module Example for Advertisement Insertion  
   Service for Free Internet Service  
     
   <?xml version="1.0"?>  
   <rulemodule>  
     <owner class="access provider">  
       <name>Comcast Free Internet Service</name>  
       <id>www.comcast.com</id>  
     </owner>  
     <protocol>http</protocol>  
     <rule processing-point="4">  
        <!- Is the requested Web resource a HTML document? -->  
        <property name="Content-Type" matches="text/html>  
          <!- Is the user a customer of the free Internet service? -->  
          <property name="User-Id" matches="^123[.]54[.]34[.]">  
            <action>icap://adserver.com/insert_ad</action>  
          </property>  
       </property>  
     </rule>  
   </rulemodule>  
        
        
   Client Rule Module Example for Language Translation and Virus  
   Scanning Service  
        
   <?xml version="1.0"?>  
   <rulemodule>  
     <owner class="client">  
       <name>Markus Hofmann</name>  
       <id>23242</ID>  
     </owner>  
     <protocol>http</protocol>  
     <rule processing-point="4">  
        <!- Is the requested Web resource text based? -->  
        <property name="Content-Type" matches="application/">  
          <action>icap://mcaffee.com/virus_scan?mode=respmod</action>  
        </property>  
     </rule>  
     <rule processing-point="4">  
       <!- Is the requested Web resource text based? -->  
       <property name="Content-Type" matches="text/">  
         <!- Does the top level domain of the origin host not  
             equal ".de"? -> Document language is probably not  
             German -> Page needs to be translated -->  
         <property name="Host" matches="[^e]$|[^d][e]$|[^.][d][e]$">  
           <action>proxylet://localhost/translate?target=de</action>  
         </property>  
       </property>  
     </rule>  
   </rulemodule>  
        
   <?xml version="1.0"?>  
   <rulemodule>  
     <owner class="content provider">  
       <name>Yahoo Inc.</name>  
       <id>www.yahoo.com</id>  
     </owner>  
     <protocol>http</protocol>  
     <rule processing-point="4">  
       <!-Does the user have a wireless Web access device? -->  
       <property name="User-Agent" matches="Nokia|Palm">  
         <!- Is the requested Web resource text based? -->  
         <property name="Content-Type" matches="text/"> 
           <action>icap://wapgateway.nl/transcode</action>  
         </property>  
       </property>  
     </rule>  
   </rulemodule>