The editor supports the use of catalogs. In the Preferences dialog you can register the catalogs you want to use. The catalogs are used to resolve all entities but are most usefull for using Public Identifiers for DTDs. The 'Create Document' dialog allows you to browse the list of Public Indentifiers available in the registered catalog files and to pick one.

The editor supports catalogs by using the catalog Library made by N. Walsh (see here). It supports the OASIS Entity Management Catalog as well as the XML Catalog format.

Here is an example of a catalog conform the OASIS Entity Management Catalog format

PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "/opt/xml/xhtml1/DTD/xhtml1-strict.dtd"
BLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "/opt/xml/xhtml1/DTD/xhtml1-transitional.dtd"
BLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "/opt/xml/xhtml1/DTD/xhtml1-frameset.dtd"
BLIC "-//Norman Walsh//DTD Simplified DocBk XML V3.1.7.1//EN" "/opt/xml/simple-docbook/sdocbook.dtd"
BLIC "-//Lunatech Research//DTD Article//EN" "article.dtd"

and here is the same one this time conform the XMLCatalog format

<XMLCatalog>catalog for "-//Morphon" public Ids
<Map PublicId="-//W3C//DTD XHTML 1.0 Strict//EN"
  HRef="/opt/xml/xhtml1/DTD/xhtml1-strict.dtd"/>
<Map PublicId="-//W3C//DTD XHTML 1.0 Transitional//EN"
  HRef="/opt/xml/xhtml1/DTD/xhtml1-transitional.dtd"/>
<Map PublicId="-//W3C//DTD XHTML 1.0 Frameset//EN"
  HRef="/opt/xml/xhtml1/DTD/xhtml1-frameset.dtd"/>
<Map PublicId="-//Norman Walsh//DTD Simplified DocBk XML V3.1.7.1//EN"
  HRef="/opt/xml/simple-docbook/sdocbook.dtd"/>
<Map PublicId="-//Lunatech Research//DTD Article//EN"
  HRef="article.dtd"/>
t;/XMLCatalog>