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).