Shield Slam / Bull Rush Question

[garabbott]

I tried looking for an answer to this question on the forums, but couldn't find one, so here goes -- I hope this doesn't come up all the time and I'm just blind or something.

For the purposes of Shield Slam, is another character (PC, NPC, or some other creature) considered a "surface" in the same way a wall is? If not, what's the procedure for bull rushing a character into another character -- are they then occupying the same space, or is the targeted character simply pushed into a different square nearby?

Shield Slam's benefit, quoted from the SRD:

"Any opponents hit by your shield bash are also hit with a free bull rush attack, substituting your attack roll for the combat maneuver check (see Combat). This bull rush does not provoke an attack of opportunity. Opponents who cannot move back due to a wall or other surface are knocked prone after moving the maximum possible distance. You may choose to move with your target if you are able to take a 5-foot step or to spend an action to move this turn."

Thanks!

[Elamdri]

This is the best I can offer you. Text from the Bull Rush Rules.

"An enemy being moved by a bull rush does not provoke an attack of opportunity because of the movement unless you possess the Greater Bull Rush feat. You cannot bull rush a creature into a square that is occupied by a solid object or obstacle. If there is another creature in the way of your bull rush, you must immediately make a combat maneuver check to bull rush that creature. You take a –4 penalty on this check for each creature being pushed beyond the first. If you are successful, you can continue to push the creatures a distance equal to the lesser result. For example, if a fighter bull rushes a goblin for a total of 15 feet, but there is another goblin 5 feet behind the first, he must make another combat maneuver check against the second goblin after having pushed the first 5 feet. If his check reveals that he can push the second goblin a total of 20 feet, he can continue to push both goblins another 10 feet (since the first goblin will have moved a total of 15 feet)."