Em9 is simply playing Em but on the 9th. fret position.
E5 is playing E on the 5th. fret position.
E7 is playing E on the 7th. fret position
E is of course just E. What did you expect! ( giggles )
4,9 5,7 oc means, play the 4th string on the 9th fret along with the 5th string on the 7th fret and strum open then closing the 5th string, while also struming the 6th string open.
And if you think my method of expressing chords is strange well, just check out the lyrics above to my song called Europa, written in Mysti's own language.
