Where are the docs for setting up internationalization?

I want to have Spanish for my shell error messages and more (like man
pages if they will exist).

So I tried setting my LANG, LC_CTYPE, LC_ALL, LC_MESSAGES and others, but
no luck.

Then I tried a different locale:

 $ export LANG=sv
 $ export LC_CTYPE=sv_SE.ISO8859-1
 $ ls -l jklsdfjkljf
 ls: jklsdfjkljf: No such file or directory

Back in August this used to tell me: "Filen eller katalogen finns ej".
Something has changed.

Any suggestions for enabling Spanish locale?

And why doesn't that "sv" locale no longer work?

   Jeremy C. Reed
   http://bsd.reedmedia.net/