1) Instead of calling the format "JIB", how about "PAR"? It can stand
for Perl ARchive or the recursive PAR ARchive. This is more memorable.
It might make sense to adopt the same naming as .jar and .epub, two very
different zipfile-as-container formats. Both use a top-level directory called
"META-INF". There's no particular technical reason to pick a given
name, so going for something that looks familiar to people may be a win.
Sounds reasonable. Like you said, there is no strong reason to pick one
name or another, so why not pick the name everyone else already uses?