a. Disappear (never to return) when their caster dies or travels farther than 100 feet from them.
b. Are considered to be on the area of ground and do not dissipate when other magic is cast.
c. A player may only have a single fixed enchantment active at a time. Casting a fixed enchantment while another fixed enchantment from the same player is already active causes both enchantments to be negated.
d. May be dispelled.