and contour layer comments, and the CycleMap mapnik slippy tiles
RP: a type of contour, hence not included in the main DB
HB: seems like (*I haven't actually looked) the edge of a crater or an escarpment, i.e. a physical ground feature, as opposed to a contour line which is arbitrarily chosen at some interval as a reflection of the elevation. Thus the edge of the depression is chosen by nature, while the placement of the contour line was chosen by a human.