Ok modes do exist within modes if that's what your wondering. Only it works out to just another mode. Take G mixolydian (GABCDEFG), now start it with the 4th note (CDEFGABC). You got the Ionian mode now, or major scale. There's really no need to think this much because you could just start off thinking of the major scale. Too much work, no benefits. Most of the scales used in western music are diatonic. The diatonic scales are major, minor, and harmonic and melodic minor. Modes are a different variation of these scales. The variation as you probably know it using the same notes but in a different interval pattern. See how it breaks down. Everything else has be noted but if you need more, check the search option. I'm sure you find more than you need to know about modes, if not just ask (as christoph has volunteered me for ;) ). But try to be more specific by using nouns instead of pronouns. Instead of "group of 'them'", say "group of modes" or whatever your asking. Just so I know exactly what your asking next time. :)