We now describe some technical details about the exact suffixes that
load tries.
This is a list of suffixes indicating (compiled or source) Emacs Lisp
files. It should not include the empty string. load uses
these suffixes in order when it appends Lisp suffixes to the specified
file name. The standard value is (".elc" ".el") which produces
the behavior described in the previous section.
This is a list of suffixes that indicate representations of the same
file. This list should normally start with the empty string.
When load searches for a file it appends the suffixes in this
list, in order, to the file name, before searching for another file.
Enabling Auto Compression mode appends the suffixes in
jka-compr-load-suffixes to this list and disabling Auto
Compression mode removes them again. The standard value of
load-file-rep-suffixes if Auto Compression mode is disabled is
(""). Given that the standard value of
jka-compr-load-suffixes is (".gz"), the standard value
of load-file-rep-suffixes if Auto Compression mode is enabled
is ("" ".gz").
This function returns the list of all suffixes that load should
try, in order, when its must-suffix argument is non-nil.
This takes both load-suffixes and load-file-rep-suffixes
into account. If load-suffixes, jka-compr-load-suffixes
and load-file-rep-suffixes all have their standard values, this
function returns (".elc" ".elc.gz" ".el" ".el.gz") if Auto
Compression mode is enabled and (".elc" ".el") if Auto
Compression mode is disabled.
To summarize, load normally first tries the suffixes in the
value of (get-load-suffixes) and then those in
load-file-rep-suffixes. If nosuffix is non-nil,
it skips the former group, and if must-suffix is non-nil,
it skips the latter group.
If this option is non-nil, then rather than stopping at the
first suffix that exists, load tests them all, and uses
whichever file is the newest.