+ * a LaTeX package, where a layout file corresponds to a LaTeX class. Or, in
+ * LyX's own terms, a module is more like an included file that can be used
+ * with various document classes. The difference is that using a module only
+ * means selecting it in the Document>Settings dialog, whereas including a
+ * layout file means layout file editing.
+ *
+ * In general, a given module can be used with any document class. That said,
+ * one module may `require' another, or it may `exclude' some other module.
+ * The requires and excludes are given in comments within the module file,
+ * which must begin roughly so:
+ * #\DeclareLyXModule{Theorems (By Section)}
+ * #DescriptionBegin
+ * #Numbers theorems and the like by section.
+ * #DescriptionEnd
+ * #Requires: theorems-std | theorems-ams
+ * #Excludes: theorems-chap
+ * The description is used in the gui to give information to the user. The
+ * Requires and Excludes lines are read by the configuration script and
+ * written to a file lyxmodules.lst in the user configuration directory.
+ *
+ * Modules can also be "provided" or "excluded" by document classes, using
+ * the ProvidesModule and ExcludesModule tags.