The Layout Editor uses a special version of the ESL compiler when it reads in the object definitions from an opened file.  The ESL compiler must understand the ESL statements it encounters.  When you open an include file by itself, separated from its usual context in an ESL program, certain definitions may be missing.

To inform the ESL compiler of definitions it will require, you specify a definition file which you have created.  A definition file can be an ESL program file or include file and contains ESL syntax.  If the definition file does contain object definitions, they will be read into the Layout Editor.

A definition file can also be a file tailored for use in the Layout Editor, perhaps including definitions of fonts or accelerator keys.  Any fonts defined in the definition file will be available in the Default Fonts and Colors dialog box.