A350 VD range indicator
 

So, the vertical display is indicated on the nav display by a blue "staple" (out to 160 nm). Occasionally the staple is not square to the track line, but slanted. Nothing to do with track or heading function, nor winds. Beers riding on the correct answer here!
Attached a photo, look right above the ETP circle.
https://cimg2.ibsrv.net/gimg/pprune....ff7d5985e9.jpg