Internal DTD Subset
The internal DTD subset is the portion of the document
type definition included directly within the document type
declaration between the [ and
] characters. The internal
DTD subset can contain markup declarations and parameter entity
references, but not conditional sections. A single document may
have both internal and external DTD subsets, which, when taken
together, form the complete document type definition. The
following example shows an internal subset, which appears
between the [ and ] characters:
<!DOCTYPE furniture_item SYSTEM "furniture.dtd"
[
<!ENTITY % bookcase_ex SYSTEM "Bookcase_ex.ent">
%bookcase_ex;
<!ENTITY bookcase_pic SYSTEM "bookcase.gif" NDATA gif>
<!ENTITY parts_list SYSTEM "parts_list.ent">
]>