From a question by the Malay translator, on IRC:
02:09 < nbliang> hi guys, new to the translation of D-I. is it that we only need to translate the 3 PO files (1
in po, 1 in po/sublevel1 and another 1 in
po/sublevel2)
The answer is *no*....
The sublevel files are derived from the packages/po files....so they
are automatically generated
This is an anticipation of a split that will occur after the release
of Etch. "sublevel1" will have the strings from the packages that are
always used in default installs for i386/amd64....which makes a very
good initial target for new translators. "sublevel2" contains all
other strings.
So, currently, please do not work on these files, just like the
README.txt file in these directories explains.