# Reserved Names

Ren’Py reserves filenames that are do not begin with a letter or number, and filenames that begin with “00”. Very specifically, filenames that start with “00” and “_” are used by Ren’Py internally.

Ren’Py reserves all names beginning with a single underscore (_). Do not use names beginning with an underscore, as that may cause your game to break in future versions of Ren’Py.

The following is a list of names that are used by Python. Re-using these names can lead to obscure problems.

The following is a list of names that are used by Ren’Py. While in some cases it makes sense to redefine these names, one should be aware that doing so can cause obscure problems.