latex209.cfg

Whenever a LaTeX document starts with \documentstyle, rather than with \documentclass, LaTeX assumes that it is a LaTeX 2.09 document and therefore processes it in `compatibility mode'. This does the following:

• sets the flag \@compatibilitytrue;
• inputs the file latex209.def;
• inputs the file latex209.cfg if it exists.

The LaTeX 2.09 set-up allowed the format itself to be customised. When making the format with iniTeX, the process ended with this request:

Input any local modifications here.

If your site did input any modifications at that point then the LaTeX2e `compatibility mode' will not fully emulate LaTeX 2.09 as installed at your site. In this case you should put all these `local modifications' into a file called latex209.cfg and put this file in the default input path at your site. These `local modifications', although not stored in the format, will then be loaded before any old-style document is processed. This should ensure that you can continue to process any old documents that made use of this local customisation.