1. common SGML DTDs and entities This package includes Document Type Definitions for HTML Level 0, 1, 2, 3, 3.2, and 4.0, DTDs representing the capabilities for popular browsers, SGML and XML declarations, and popular XML DTDs. Also included are ISO standard entities (SGML and XML), HTML standard entities, and other generally useful sets of entities. Access to these data files is facilitated by the inclusion of an SGML catalog file which defines a default SGML declaration and a default DTD for documents whose DOCTYPE is 'html', and which links system identifiers to public identifiers for other SGML DTDs and entity sets. No setup is required by the user, due to the Debian SGML/XML common layer (see the sgml-base package) From Debian 3.0r0 APT