There are many common chord symbols and notation for musical ideas. If you want someone to play an A major chord, just an
A denotes an A major chord. If you wanted someone to play an A minor chord,
Am is the symbol you would use. If you want someone to play an A "power chord" , you would notate
A5. The notation for music is very in extensive, but I do not know the standard notation for an A octave. Is there any notation for an octave besides the P8 used in interval notation? Is an octave uncommon enough to where there is no symbol for it?
EDIT: I don't think I was clear enough. Is there any notion for octaves that can be used on lead sheets? i.e. very simple notation that shows the note and the fact that only an octave is to be played. Does it exist?