DTDs for Record-Like Documents
DTDs for record-like documents are very straightforward. They make heavy use of sequences, occasional use of choices, and almost no use of mixed content. Example 3-6 shows such a DTD. Since this is a small example, and since it’s easier to understand when both the document and the DTD are on the same page, we’ve made this an internal DTD included in the document. However, it would be easy to extract it and store it in a separate file.
<?xml version="1.0"?> <!DOCTYPE person [ <!ELEMENT person (name+, profession*)> <!ELEMENT name EMPTY> <!ATTLIST name first CDATA #REQUIRED last CDATA #REQUIRED> <!-- The first and last attributes are required to be present but they may be empty. For example, <name first="Cher" last=""> --> <!ELEMENT profession EMPTY> <!ATTLIST profession value CDATA #REQUIRED> ]> <person> <name first="Alan" last="Turing"/> <profession value="computer scientist"/> <profession value="mathematician"/> <profession value="cryptographer"/> </person>
The DTD here is contained completely inside the internal DTD
subset. First a person ELEMENT
declaration states that each person
must have one or more name
children, and zero or more profession
children, in that order. This
allows for the possibility that a person changes his name or uses
aliases. It assumes that each person has at least one name but may
not have a profession.
This declaration also requires that all name
elements precede all profession
elements. ...
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