gnatkr command has the form
$ gnatkr name [length]
name can be an Ada name with dots or the GNAT name of the unit,
where the dots representing child units or subunit are replaced by
hyphens. The only confusion arises if a name ends in
gnatkr takes this to be an extension if there are
no other dots in the name and the whole name is in lowercase.
length represents the length of the krunched name. The default when no argument is given is 8 characters. A length of zero stands for unlimited, in other words do not chop except for system files which are always 8.
The output is the krunched name. The output has an extension only if the original argument was a file name with an extension.