L-shaped sign for hand distribution (piano)
Sometimes, in piano music, editors add marks to indicate that a note or part of a chord is to be played by the other hand, even if the score doesn't expressely say so.
See the example:
It's important to note that the sign is to be anchored to the individual note, not to a chord (eg. like a staccatto, tenuto, accent...).
It would e a good idea to place the sign in the fingerings palette.