As an
extension to that query, a major 9th also has a natural (non-flattened) 7th note too.
^^^ weak attempt at humour.
Here's an excellent link for looking up chords you're unsure of (I've favourited it):
Major 7th Chords, and all about Guitar Chords
Or for an index of them:
Browse Chord Mine by Chord Types
What a great link.
So it seems to go like this:
13th = 1,3,5,
b7,9,11,13
Major 13th = 1,3,5,
7,9,11,13
Minor 13th = 1,b3,5,
b7,9,11,13
So what's the rule of thumb? It seems to be that if you are playing simple chords, the Major refers to the natural 3rd (3), but if you are playing extensions ie chords with a 7th and more notes, the major refers to the natural 7th (7). Is that always true?