Common header elements:
X: index number, required in some software [e.g. X:1]T: title [e.g T: Happy Birthday]M: meter, required [e.g. M:C, M:4/4, M:3/4]L: default note length [e.g. L:1/2, L:1/4, L:1/8]Q: tempo [e.g. Q:120, Q:1/8=120, Q:1/4=60]K: key signature, required [e.g. K:G, K:Gm]V: voice, can set the clef [e.g. V:1 name=Violin, V:2 name=Cello clef=bass]Common notation elements:
CDEFGAB, top octave cdefgab [e.g. C = middle C]z rest, down an octave, ' up an octave [e.g. C, or c']^ sharps, _ flats [e.g. ^c or _c]/ dividing number [e.g. a2 or a/2]a b c versus abc]| barline, |] double bar, |: repeats :|For help, check the ABC Tutorial.