Definition for our world: Laying face down.
3ed Dungeons and Dragons
Showing complete ignorance about what the word means, prone in the rules simply means laying horizontal. Differences in situation due to being prone or supine are not even touched upon. Considering that the 3ed Dungeons and Dragons do not even consider facing, it really is not that surprising.
A character in this state suffers a –4 penalty on Attack rolls (only range weapon usable is crossbow – although can use without penalty). Opponents using melee weapons gain a +4 to hit a prone opponent, although those using range weapons suffer a –4 penalty to hit. Standing up from prone is a move equivalent action.