odt file instant open

[Olwe Melwasul <hercynianforest@gmail.com>]

I'm trying to grok the open document format, so I took the first wild
and crazy step of simply trying to open it in Emacs (23.2.1) -- and it
opened up to a "Zip-Archive Narrow" view of all the files contained
therein Poking around on the Internet, I found that Emacs
automatically unpacks a .odt file, which is nothing more than a zip
file. My question is this: How is Emacs doing this? What code is
running (what .el is invoked) to make this happen? Also, where might
documentation be on how to control this zip/unzip functionality with
elisp. I don't want to do a system call, i.e., reinvent the wheel.

O