If altitude is omitted from a coordinate string, e.g. (122.917, 49.2623) then the default value of 0 (approximately sea level) is assumed for the altitude component, i.e. (122.917, 49.2623, 0).
In some systems, shunting-signal identification signs are omitted; instead, a shunting sign uses purple (instead of white) lights in a shunting signal.