Each round, a dying character makes a Fortitude
saving throw (DC 20). If the save fails, the character loses 1
hit point and must make another save on his or her turn the next round.
If the save succeeds, the character becomes stable. A stable character stops losing
hit points every round, but remains unconscious.
If no one tends to the stable character (see below), he or she remains unconscious for 1 hour, at which point he or she makes a Fortitude save (DC 20). If the save succeeds, the stable character regains consciousness, becoming disabled (see above). The character's current
hit point total remains where it is, however, even though it's negative. If the save fails, the character remains unconscious.
An unaided stable, conscious character who has negative
hit points (and is disabled) doesn't heal naturally. Instead, each day the character makes a Fortitude save (DC 20) to start recovering
hit points naturally that day; if the save fails, he or she loses 1
hit point.
Once an unaided character starts recovering
hit points naturally, the character is no longer in danger of losing additional
hit points (even if his or her current
hit point total is still negative).