Wolfenstein 3D levels

[spec@vax2.concordia.ca (Mitchell Spector)]

    I began playing Wolf 3D over the past week, starting with Mission 
Zero ("Original Encounter") and thus far made it up to to level 6-4.
I'm curious though, has the game automatically skipped up to the next 
scenario as I've progressed--am I now on Mission 6 ("Final Encounter")
or am I just on the sixth floor of mission zero? I lost track of how
many levels I've gone through already. :)

    The reason I ask is I briefly loaded Mission 6 (and a few others)
and it appears to be identical, even as much as the level indicator 
saying "6-1" right when you start. I did notice I didn't get to play 
any of the levels from Mission 1 (the the original IBM PC levels)
which makes me wonder if you do have to load the scenarios separately. 
Hmm, how many levels are there in total? Is it 90--the same as it was 
back in 1993-94 when Wolf 3D GS was first started?

Mitchell Spector
spec@vax2.concordia.ca