Question on ANY (its use in RDF)
Roger L. Costello
costello at mail11.mitre.org
Sun Jan 24 15:06:13 GMT 1999
I have a question about the ANY type. It is my understanding
that an element defined to be of type ANY can contain any
element that is defined *within* the DTD (i.e., it cannot use
elements that are not defined in the DTD). Correct?
Consider the RDF.dtd (at bottom). It defines an element rdf:Description
that is of type ANY. Here is an example RDF XML document:
<?xml version="1.0"?>
<!DOCTYPE rdf:RDF SYSTEM "RDF.dtd">
<rdf:RDF xmlns:cat="http://db2.ibm.com"
xmlns:rdf="http://www.w3.org/schemas/rdf-schema">
<rdf:Description about="http://db2.ibm.com/catalogs">
<cat:tables>
<rdf:Bag>
<rdf:li>
<rdf:Description><systables cat:tname="SYSTABLES"
cat:owner="SYSIBM " cat:colnos="38"/></rdf:Description>
</rdf:li>
<rdf:li>
<rdf:Description><syscolumns cat:tname="SYS < COLUMNS"
cat:owner="SYSIBM " cat:colnos="34"/></rdf:Description>
</rdf:li>
</rdf:Bag>
</cat:tables>
</rdf:Description>
</rdf:RDF>
How can rdf:Description contain the element cat:tables? It is
not defined in rdf.dtd. I thought that ANY says that the element
can contain any elements defined *within* the DTD? /Roger
Here is RDF.dtd:
<!ENTITY % container "( rdf:Seq | rdf:Bag | rdf:Alt )">
<!ENTITY % rdfObj "( rdf:Description | %container; )">
<!ELEMENT rdf:RDF ( %rdfObj; )* >
<!ENTITY % property "ANY">
<!ELEMENT rdf:Description %property;>
<!ATTLIST rdf:Description
ID NMTOKEN #IMPLIED
about CDATA #IMPLIED
aboutEach CDATA #IMPLIED
bagID NMTOKEN #IMPLIED
>
<!ENTITY % collmember "rdf:li">
<!ELEMENT rdf:Seq ( %collmember; )*>
<!ATTLIST rdf:Seq
ID NMTOKEN #IMPLIED>
<!ELEMENT rdf:Bag ( %collmember; )*>
<!ATTLIST rdf:Bag
ID NMTOKEN #IMPLIED>
<!ELEMENT rdf:Alt ( %collmember; )+>
<!ATTLIST rdf:Alt
ID NMTOKEN #IMPLIED>
<!ENTITY % value "( %rdfObj; | PCDATA )">
<!ELEMENT rdf:li ( %value; )>
<!ATTLIST rdf:li
resource CDATA #IMPLIED>
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