"_New" vs. N_("New") vs. N_("_New")

[Ian Peters <itp-gnome-list geodesic res cmu edu>]

Hello.  Can someone quickly explain to me the different uses of:

- "_<string>"
- N_("<string>")
- N_("_<string>")

inside GNOME applications?  I've tried looking through other people's
sources, and I've found no noticeable rules to follow...it seems to be
pretty much arbitrary.

-- 
Ian Peters
ipeters@acm.org