Who can read sheet music ?

I read and write but learned it rather late (mid 20 something). And, I'm a guitar player

Sure, it's not necessary to read/write to be a good musician but it certainly helps and makes life easier. I would probably not have been able to play Bach's lute music without the knowledge of reading music. And, it's so much easier to talk to other musicians and get your ideas across (you don't have to sit in front of people showing/playing what you want them to play).

goose wrote: Mixolydian: tone, tone, semi, tone, tone, semi, tone Or: tonic, major second, major third, perfect fourth, perfect fifth, major sixth, flattened seventh, octave Or all the white/natural notes starting on G

mmmmm mixolydian, reading music is like reading a book its just a new way of looking at it.  I've been reading and writing music for the last 13 years now.  The real pain is on the spot transposing

Dorian:

tone, semi, tone, tone, tone, semi, tone

Or:

tonic, major second, minor third, perfect fourth, perfect fifth, major sixth, flattened seventh, octave

Or all the white/natural notes starting on D

The first two bits might not be right, but they can be worked out from the third, which is right. In practical terms, the Dorian can be seen as the "minor version" of the Mixolydian, although that's simplifying matters slightly.