An inclusion does not appear in the content model so it is not part of the production rule for the element. When an inclusion is encountered a parser for the inclusion is called and the inclusion is parsed. To know which parser to call a table is generated with pairs consisting of the inclusion's starttag and the parser for the inclusion. This is generated on the file with name ``incl.i''. To refer to a parser (a C-function), the parser must be defined extern. This is done on the file ``incl.ext''.
For information on the above procedures see ``stack.gen''.