A.5 General Architecture

A.5.5 ID immediate referent type control

The attribute form ireftype allows applications to control the immediate referent of ID references.

An ID reference is an attribute whose declared value prescription is IDREF or IDREFS, or an attribute or data content that is declared to contain ID references by a lextype constraint. Attribute ID references are specified by the attribute names, and content ID references by the reserved name "#CONTENT". The reserved name "#ALL" means "all ID references in the attribute values and data content of this element type".

The attribute ID immediate referent element type (ireftype) associates names of referential attributes (or #CONTENT) with element types to which their immediate targets must conform. The element types can be specified as a single GI, possibly followed by an occurrence indicator; a model group of GIs; or the reserved word #ANY, which signifies that any target is acceptable for the corresponding attribute. If the irefmodel option of the General Architecture is supported, model groups can be any valid SGML model group. When the list of element types is not a repeating OR group or when it is a single GI without an occurrence indicator, the reference is limited to a single instance of one of the named types. If the refmodel option is not supported, model groups are limited to single (possibly repeatable) GIs or repeating or non-repeating OR groups of GIs.

NOTE 476 In other words, a simple list of possible target GIs, possibly repeating.

The constraints associated with #ALL can be overridden for particular referential attributes by specifying element types for them individually.

The referenced element type constraints apply to the immediate target of the reference. If the reference is to a location path, the constraints apply to the first location address in the path, not the objects ultimately addressed by the location path.

             <!-- ID Immediate Referent Element Type -->
<![ %ireftype; [
<!attlist
-- ireftype --    -- ID immediate referent element type --
                  -- Clause: A.5.5 --
   #ALL

   ireftype       -- ID immediate referent element type --
      CDATA       -- Lextype: (("#ALL",(GI|modelgroup|"#ANY"))?,
                               (ATTORCON,(GI|modelgroup|"#ANY"))*) --
                  -- Constraint: a given ATTNAME or #CONTENT can occur
                     only once; types apply to immediate object of
                     address. --
                  -- Constraint: model groups limited to repeating
                     or non-repeating OR groups if irefmodel option not
                     supported. Tokens in model groups must be GIs. --
      "#ALL #ANY" -- Constant --
>
]]><!-- ireftype -->

			Copyright © 1992, 1997 International Organization for Standardization. All rights reserved. This electronic document is for use during development and review of International Standards. Official printed copies of International Standards can be purchased from the ISO and the national standards organization of your country.
Next Clause	Previous Clause