I'm writing out the Bärenreiter version of Bach Concerto for two violins BWV 1043 on Musescore, and have come across an odd symbol in the left hand piano part.
Here is a picture - the elongated L symbol just before the G#:
At a guess, it looks like it is separating a voice, but I'm not sure what it's called so I can't find it in the Musescore palettes.