from 4.02:
All the player’s units which were disabled before
the last enemy turn by ramming or enemy fire now recover
automatically.
from 7.11:
A unit disabled by ramming or enemy fire recovers after one full
enemy turn has passed. If it becomes disabled on an enemy turn, . . .
There is no terrain-induced disabling, so we don't need to draw the distinction. All disabled units will have been disabled by ramming or enemy fire during an enemy turn. Or am I overlooking any possibilities for when/how a unit might get disabled in strict Ogre?