Disabled (0 Hit Points)

When a character's current hit points drop to exactly 0, the character is disabled. The character is not unconscious, but he or she is close to it. The character can only take a single move or attack action each turn (but not both, nor can the character take full-round actions). The character can take nonstrenuous move actions without further injuring his or herself, but if the character attacks or perform any other action the GM deems as strenuous, the character takes 1 point of damage after completing the act. Unless the activity increased the character's hit points, the character is now at -1 hit points, and is dying.
Healing that raises the character above 0 hit points makes him or her fully functional again, just as if the character had never been reduced to 0 or lower.
A character can also become disabled when recovering from dying. In this case, it's a step up along the road to recovery, and the character can have fewer than 0 hit points (see Stable Characters and Recovery).