External module in the base DTD Suite that names all the external modules (except itself) that are part of the base DTD Suite (Note: This module does not declare itself, the DTD, any of the Book customization modules, or the Book-DTD-specific Module of Modules which declares the Book customization modules.)
A DTD selects from the named modules by referencing the external Parameter Entities defined in the Suite Module of Modules. To include a set of elements (such as all the lists or the MathML elements), a DTD references the external Parameter Entity of the module that contains those elements.
<!ENTITY % modules.ent PUBLIC "-//NLM//DTD Archiving and Interchange DTD Suite Module of Modules v2.1 20050630//EN" "modules.ent" >
bookcollection.dtd / book.dtd