Mac, by internal name I mean the second word in the first line of a channel, actor, or prop, etc, as indicated in the postes above. In other words the name used internally by Poser to distinguish these things, as opposed to the dial name which occurs in the 'name' line. As to determining the height of a wall, you could also use the (shameless plug) Ultimate Callipers, available in the Free Stuff, which will give you the height to the nearest 64th of an inch, or 100th of a millimeter, without the need of any mental arithmetic :)