hi ben,
the TOC arrow is part of the VNAV thing with all the other vnav arrows indications still missing...the whole vnav thing is really a black art (words used by many real pilots :) ) i asked by myself many times JL about the missing vnav implementation. he said he needs time to rework the whole vnav which will be a nightmare...this has been said months ago, so i hope it's going to happen in the close future...of course just my tought.
all the best
fil