If you feel the need to make a version of LaTeX that differs from
the standard version in ways that are not possible using the above
configuration possibilities, then you should first read
Modifying LaTeX in the file
will probably make you realise that you do not have any such need.
Thus we are sure that you will never need to create a non-standard version and, even if you do create one, we hope that you will not distribute such a version. Nevertheless, you are permitted to do this provided you take great care to do the following:
\typeoutbanners': i.e. those produced by all the non-standard files in your version and by the format;