From:  http://www.datachannel.com/schemas/pml.dtd
Date:  1999-09-13
<!-- ............................................................... -->
<!-- Portal Markup Language (Version 0.9) .......................... -->
<!-- Copyright (C) 1999, DataChannel, Inc. ......................... -->
<!-- ............................................................... -->

<!--
  This DTD describes portal related data and metadata. The objective is to
  allow portals of the same or of different manufacturers to exchange
  information about the information objects, users, groups, access controls
  subscriptions and notifications managed by the system. Is is not within
  the scope of this document to provide a protocol for the syndication
  process itself. 

  Please note that this is work in progress. I may contain inconsistencies
  and syntactical errors.
-->

<!-- ............................................................... -->
<!-- Common attributes ............................................. -->
<!-- ............................................................... -->

<!ENTITY % standardResource.att
       'NAME            CDATA   #REQUIRED
       URI             CDATA   #REQUIRED
        LOCKEDON        CDATA   #IMPLIED
	LOCKEDBY        CDATA   #IMPLIED
        LOCKDURATION    CDATA   #IMPLIED
        CREATEDBY       CDATA   #REQUIRED
        CREATEDON       CDATA   #REQUIRED
        MODIFIEDBY      CDATA   #REQUIRED
        MODIFIEDON      CDATA   #REQUIRED
        DEPTH           CDATA   #REQUIRED
        CLASS           CDATA   #REQUIRED
        USERRIGHTS      CDATA   #REQUIRED'>

<!-- ............................................................... -->
<!-- Common directory attributes ................................... -->
<!-- ............................................................... -->
<!--     active       - Is the user/group still active in the system -->
<!--     import       - Is the user/group managed by the portal      -->
<!--                    or by a third party (e.g. directory service) -->
<!-- ............................................................... -->

<!ENTITY % directory.att
       'ACTIVE          CDATA   #IMPLIED
        IMPORT          CDATA   #IMPLIED'>
        
<!-- ............................................................... -->
<!-- Classes of privileges ......................................... -->
<!-- ............................................................... -->

<!ENTITY % rights.class
    "ALLRIGHTS | READ | READCONTENT | WRITE | WRITECONTENT |
    DELETE | CREATECHILD | DELETECHILD | CREATESUBCONTAINER |
    DELETESUBCONTAINER | WRITEOWNER | READACL | WRITEACL" >
   
<!-- ............................................................... -->
<!-- General elements .............................................. -->
<!-- ............................................................... -->
<!-- The principle classes of objects in a portal:                   -->
<!--     Storage      - Management of information objects            -->
<!--     Directory    - Management of users                          -->
<!--     Notification - Proactive notification about changes to      -->
<!--                    information objects                          -->
<!--     Subscription - Manage the associate between notifications   --> 
<!--                    and users                                    -->
<!-- ............................................................... -->
    
<!ELEMENT RIO (STORAGE+, DIRECTORY+, (NOTIFICATIONS | SUBSCRIPTIONS )* ) >

<!-- ............................................................... -->
<!-- Storage service elements ...................................... -->
<!-- ............................................................... -->

<!ELEMENT STORAGE ( ACL, (FOLDER | LINK | CONTENT)* ) >
<!ATTLIST STORAGE
    %standardResource.att; >

<!-- ............................................................... -->
<!-- Portal Folder ................................................. -->
<!-- ............................................................... -->
<!-- A folder is a container for portal objects. Folders are not     -->
<!-- bound to one single physical location but do rather collect     -->
<!-- objects from various sources.                                   -->
<!-- Folders can contain other folders, links or content objects.    -->
<!-- ............................................................... -->

<!ELEMENT FOLDER ( ACL, (FOLDER | LINK | CONTENT)* )>
<!ATTLIST FOLDER
    %standardResource.att; >

<!-- ............................................................... -->
<!-- Link ................................ ......................... -->
<!-- ............................................................... -->
<!-- A pointer to an information object.                             -->
<!-- Storage is not controled by the portal.                         -->
<!-- ............................................................... -->
    
<!ELEMENT LINK ( ACL )>
<!ATTLIST LINK
    %standardResource.att; >

<!-- ............................................................... -->
<!-- Content ............................. ......................... -->
<!-- ............................................................... -->
<!-- A pointer to an information object.                             -->
<!-- Storage device can be accessed by the portal.                   -->
<!-- Storage attributes control the read and write access.           -->
<!-- ............................................................... -->
    
<!ELEMENT CONTENT ( ACL )>
<!ATTLIST CONTENT
    STORAGEWRITEURL         CDATA   #IMPLIED
    STORAGEREADURL          CDATA   #IMPLIED
    STORAGELOGINUSERNAME    CDATA   #IMPLIED
    STORAGELOGINPASSWORD    CDATA   #IMPLIED
    %standardResource.att; >


<!-- ............................................................... -->
<!-- Directory service elements .................................... -->
<!-- ............................................................... -->
<!-- The principle classes of objects related to directories:        -->
<!--     Users        - Individual users of a system                 -->
<!--     Groups       - Collections of users                         -->
<!-- ............................................................... -->

<!ELEMENT DIRECTORY ( ACL, USERS, GROUPS )>
<!ATTLIST DIRECTORY
    %directory.att;
    %standardResource.att; >
    
<!ELEMENT USERS ( ACL, USER* )>
<!ATTLIST USERS
    %directory.att;    
    %standardResource.att; >
    
<!ELEMENT USER ( acl ) >
<!ATTLIST USER
    %directory.att;
    %standardResource.att; >
    
<!ELEMENT GROUPS ( acl, GROUP* )>
<!ATTLIST GROUPS
    %directory.att;
    %standardResource.att; >

<!ELEMENT GROUP ( acl, (USERREFS | GROUPREFS)* )>
<!ATTLIST GROUP
    %directory.att;
    %standardResource.att; >
					
<!--
    NOTE: <USERMAILBOX> can only exist in a subtree of <NOTIFICATIONS>
          <USERREF> can only exist in a subtree of <DIRECTORY>
-->
<!ELEMENT USERREFS ( acl, ( USERREF* | USERMAILBOX* ))>
<!ATTLIST USERREFS
    %directory.att;
    %standardResource.att; >
    
<!ELEMENT USERREF ( acl ) >
<!ATTLIST USERREF
    %directory.att;
    %standardResource.att; >
    
<!--
    NOTE: <GROUPMAILBOX> can only exist in a subtree of <NOTIFICATIONS>
          <GROUPREF> can only exist in a subtree of <DIRECTORY>
-->
<!ELEMENT GROUPREFS ( acl, ( GROUPREF* | GROUPMAILBOX* ))>
<!ATTLIST GROUPREFS
    %directory.att;
    %standardResource.att; >
    
<!ELEMENT GROUPREF ( acl ) >
<!ATTLIST GROUPREF
    %directory.att;
    %standardResource.att; >   

<!-- ............................................................... -->
<!-- Notification service elements ................................. -->
<!-- ............................................................... -->

<!ELEMENT NOTIFICATIONS ( ACL, USERREFS, GROUPREFS )>
<!ATTLIST NOTIFICATIONS 
    %standardResource.att; >
    
<!ELEMENT USERMAILBOX ( ACL, NOTIFICATION* ) >
<!ATTLIST USERMAILBOX
    %standardResource.att; >
    
<!ELEMENT NOTIFICATION ( ACL ) >
<!ATTLIST NOTIFICATION
    %standardResource.att; >
    
<!ELEMENT GROUPMAILBOX ( ACL, NOTIFICATION*)>
<!ATTLIST GROUPMAILBOX
    %standardResource.att; >  

<!-- ............................................................... -->
<!-- Subscription service elements ................................. -->
<!-- ............................................................... -->
<!-- A subcription associates a resource with a criterion that       -->
<!-- triggers a notification and a delivery method/protocol.         -->
<!-- ............................................................... -->

<!ELEMENT SUBSCRIPTIONS ( ACL, RESOURCE* )>
<!ATTLIST SUBSCRIPTIONS
    %standardResource.att; >
    
<!ELEMENT RESOURCE ( ACL, SUBSCRIPTION* )>
<!ATTLIST RESOURCE
    %standardResource.att; >
    
<!ELEMENT SUBSCRIPTION ( ACL, CRITERION+, DELIVERY+ )>
<!ATTLIST SUBSCRIPTION
    ACTION          CDATA   #REQUIRED
    TARGET          CDATA   #REQUIRED
    %standardResource.att; >
    
<!ELEMENT CRITERION ( ACL ) >
<!ATTLIST CRITERION
    TYPE            (XQL | JAVASCRIPT)  #REQUIRED
    EVALUATION      CDATA               #REQUIRED
    %standardResource.att; >
    
<!ELEMENT DELIVERY ( ACL ) >
<!ATTLIST DELIVERY 
    TYPE            (RIO | SMTP)    #REQUIRED
    ADDRESS         CDATA           #IMPLIED
    FORMATTER       CDATA           #IMPLIED
    %standardResource.att; >   

<!-- ............................................................... -->
<!-- Access Control elements ....................................... -->
<!-- ............................................................... -->

<!ELEMENT ACL   ( OWNER+, ACE* ) >
<!ELEMENT ACE   ( RIGHTS | PRINCIPAL+) >
<!ELEMENT OWNER ( PRINCIPAL+ ) >

<!--
    NOTE: '<ALLOWNERS/>' cannot exist in a '<PRINCIPAL>' underneath an '<OWNER>'
-->
<!ELEMENT PRINCIPAL ( #PCDATA | ALLPRINCIPALS | ALLAUTHPRINICPALS | ALLOWNERS)*>

<!ELEMENT ALLPRINCIPALS     EMPTY>
<!ELEMENT ALLAUTHPRINICPALS EMPTY>
<!ELEMENT ALLOWNERS         EMPTY>

<!-- ............................................................... -->
<!-- Privileges can be either granted or denied.                     -->
<!-- Grant permissions override deny permissions.                    -->
<!-- ............................................................... -->

<!ELEMENT RIGHTS (GRANT, DENY )>
<!ELEMENT GRANT  ( ( %rights.class; )* )>
<!ELEMENT DENY   ( ( %rights.class; )* )>

<!ELEMENT ALLRIGHTS             EMPTY>
<!ELEMENT READ                  EMPTY>
<!ELEMENT READCONTENT           EMPTY>
<!ELEMENT WRITE                 EMPTY>
<!ELEMENT WRITECONTENT          EMPTY>
<!ELEMENT DELETE                EMPTY>
<!ELEMENT CREATECHILD           EMPTY>
<!ELEMENT DELETECHILD           EMPTY>
<!ELEMENT CREATESUBCONTAINER    EMPTY>
<!ELEMENT DELETESUBCONTAINER    EMPTY>
<!ELEMENT WRITEOWNER            EMPTY>
<!ELEMENT READACL               EMPTY>
<!ELEMENT WRITEACL              EMPTY>