HelpTag expects a primary control file named volume.htg or volume.ctg, where volume is a name you choose. File extensions are used to distinguish whether the control file references shorthand (.htg) or formal (.ctg) markup.
Be sure your volume name is unique and meaningful. If your volume name is too general, it may conflict with another volume that someone else has created. If you are writing application help, one recommended practice is to use the application's class name. For example, the class name for the Icon Editor is Dticon, so its help volume is named Dticon.htg.
The volume.htg file contains entity declarations and entity references to files that make up the help volume. Although HelpTag expects a single volume.htg file as input, you can separate your work into multiple source files. Additional files are sourced into the volume.htg file using file entities. A file entity is like a pointer to another file. That file, in effect, is inserted wherever the entity's name appears in the volume.htg file. The referenced files can also contain entity references to yet other files. (Entities can also be used to reference text strings.)
Suppose a help volume has six chapters and each chapter is a separate file. The files are: HomeTopic, Metainfo, TOC, Tasks, Reference, and Glossary. The volume.htg file for the help volume includes file entities for each of the six files and a list of entity references that instruct the HelpTag software to process the files.
<!entity HomeTopic FILE "HomeTopic"> <!entity MetaInformation FILE "Metainfo"> <!entity TableOfContents FILE "TOC"> <!entity Tasks FILE "Tasks"> <!entity Reference FILE "Reference"> <!entity Glossary FILE "Glossary"> &HomeTopic; &MetaInformation; &TableOfContents; &Tasks; &Reference; &Glossary;
The details of running HelpTag are covered in "To Create a Run-Time Help Volume".