use a settings file -- but it moves away from the elegance of having a single file. Also, the location of such a file would be contentious -- it could be in a standard linux location like ~/.pyisocalc/settings.conf or ~/.local/share/pyisocalc but Windows/Mac users would have to use a different location
Have the program edit its own source code to add abbreviations -- neat idea, but may not be appreciated by e.g. md5sum based security solutions that monitor executables for change. Not likely to be a real issue.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Two conceivable approaches: