YADS Model Schema - EBNF

This is the EBNF schema for the YADS model. 


  <?xml version="1.0" encoding="UTF-8"?>
  <!--
  
    YADS - EBNF
  
    This document describes YADS - A Description Service
    in an Extended BNF.
  
    ==
  
    // From RDF Schema for YADS

    Resource:     doi:1014/yads-schema-2002-04-03
    Comment:      RDF Schema for YADS - A Description Service
    Author:       Tony Hammond <tony_hammond@harcourt.com>
    Revision:     April 3, 2002 - Tony Hammond
  


    ==

    (*
       In the following, EBNF ISO/IEC 14977 : 1996(E) (for a draft
       see eg <http://www.cl.cam.ac.uk/~mgk25/iso-14977.pdf>) is
       used to define a YADS resource description.
    
       Note that this EBNF is an abstract rule set and applies only
       to the actual content of the resource description and not to
       any markup or serialization used to convey that description.
    
       For example, in the generic XML serialization of YADS, this
       EBNF applies only to the element content without markup tags.
    
       In EBNF ISO/IEC 14977 : 1996(E)
    
         [ ] means zero or one
    
         { } means zero or more
    *)
    
    (* Structural elements for aggregating resources and properties. *)
    
    yads = { ( item | nest ) } ;
    
    item = {property}, ( resource | collection ), {property} ;
    
    nest = ( {property}, resource, {property}, collection, {property} )
           | ( {property}, collection, {property}, resource, {property} ) ;
    
    (* Structural element for aggregating structural elements. *)
    
    collection = group, {group} ;
    
    group = item | nest ;
    
    (* Resource element as per RFC 2396. *)
    
    resource = any-uri ;
    
    (* Property elements attributing metadata to resources. Note that
       only one property element of each type can be meaningfully applied
       to a nest or to an item.  *)
    
    property = access | detail | directive | label | role | service | type ;
    
    (* An access point in the resource hierarchy. *)
    access = string ;
    
    (* A human readable description. *)
    detail = string ;
    
    (* A directive for a service component. *)
    directive = string ;
    
    (* A presentational element for a display service. *)
    label = string ;
    
    (* A relationship role to another resource. *)
    role = string ;
    
    (* A service component. *)
    service = string ;
    
    (* An application-specific type. *)
    type = string ;
    
    (* Legitimate values for URI must comply to the syntax
       defined in <http://www.ietf.org/rfc/rfc2396.txt?number=2396>. *)
    
    (* Productions for "any-uri" and "string" terminals need to be added. *)
  
  -->
  <yads/>