load-file-rep-suffixes

load-file-rep-suffixes is a variable defined in `C source code'.
Its value is

("" ".gz")

Documentation:
List of suffixes that indicate representations of the same file.
This list should normally start with the empty string.

Enabling Auto Compression mode appends the suffixes in
`jka-compr-load-suffixes' to this list and disabling Auto Compression
mode removes them again. `load' and related functions use this list to
determine whether they should look for compressed versions of a file
and, if so, which suffixes they should try to append to the file name
in order to do so. However, if you want to customize which suffixes
the loading functions recognize as compression suffixes, you should
customize `jka-compr-load-suffixes' rather than the present variable.