Documentation for "encodings" is mostly wrong
The manpage implies it is possible to specify the directory/ies for encodings when generating fonts.scale/fonts.dir. This is not the case:
doDirectory calls checkEncoding for each found face and known encoding from encodings_array. For each encoding, it tries to load the encoding via libfontencs FontEncFind(encoding, NULL). Not specifying a filename as second parameter causes libfontenc to use its compile time default encodings dir (if not overridden via env variable "FONT_ENCODINGS_DIRECTORY"), e.g. /usr/share/fonts/encodings/encodings.dir.
The specified encodings are only processed after any fonts.dir/fonts.scale.
As implemented "-e" is only useful in combination with "-n", i.e.
- mkfontscale -n -e /usr/share/fonts/encodings/ -e /usr/share/encodings/large/ /usr/share/encodings/
- mkfontscale /usr/share/fonts/truetype/
- mkfontscale -b -s
Also the man page mentions the encodings list 'is written to an "encodings.dir" file in every font directory.'. Though technically correct, this is quite pointless as it is not read by mkfontscale, and as far as I can see, also not required by the X server.