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