built-in shelf
xml-dtds is a built-in shelf used to store compiled XML DTDs. These items are typically created and
used as follows:
creating with document) assigns an item of the shelf to be the
compiled DTD. If the item did not previously exist, it is created.
instance or with document-element) uses an
item of the xml-dtds shelf. An item of this shelf can be used any number of times. Items can even be
used simultaneously for nested do xml-parse actions.
Apart from this special syntactic support, the xml-dtds shelf behaves like an ordinary shelf of type
xml-dtd.