Some mapping info...

[S8NSSON]

Most of you probably already know this stuff, but some of you may not.

Highest object a character can walk over: 18 units
Highest object a character can jump over: 60 units¹
Lowest object a character can walk under: 57 units
Lowest object a character can crawl under: 29 units

¹A character will make a 60 unit jump, but will pause slightly on the edge of the object. 58 units is ideal for smooth jumping.

DISCLAIMER: These tests were done in BSP on flat surfaces. I hope your results do not vary. If any of this information differs from what you've discovered please correct me. S8NSSON, or any of his affiliates, takes no responsibilities for injuries to your character as a result of any of the information found in this post. Please use caution when putting your character through rigorous testing. Thier little digital legs can be quite fragile.

[jitspoe]

The highest a character can jump actually depends on both the framerate and the players position on the Z axis, due to bugs/imprecisions in the phyiscs calculations.  It can range from about 58 to nearly 78.  If possible, build everything in your map above the z axis so it doesn't give people with high framerates the advantage.

See this thread for more details.

[S8NATHOME]

Thanx Jitspoe.
That was some of the most informative and interesting reading!