Nope, but it does make it easier, considering a missions often consist of scripts, briefings & overviews, maybe sound and music...well, a mess
That is, un-packed (un PBO'ed). And packing it isn't really and option if you want to continue editing on it, so...
then just unzip the thing, make sure the folder name's got all the extensions right and so forth...
Ain't really the forum for these kinds of things, but you got your answer so all's well, nyah?
Happy editing! ;D
Wolfrug out.