Environment variables?

[Leif Gregory]

In configuring various menu items and default programs to open when
certain things are double-clicked I've run across a number of different
variable arguments (maybe not the right term), stuff like %m, %u, %l
etc.

Are these unique to each program, are they arbitrary, specific to
Nautilus or what? If they aren't arbitrary or specific to the
application, is there a list somewhere showing what they are and what
they're used for?

Some real examples:
firefox %u
kopete -caption "%c" %i %m %u
vinagre %U

Thanks.

-- 
Leif Gregory
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