Casting Time - The amount of time it takes for you to cast a spell,
in rounds.  A spell with 1 round casting time takes 1 full round of
casting before the spell effect goes off, and it works the same for
any number of rounds.  During the casting time of the spell, you are 
assumed to be acting out the spells verbal and somatic components.
This is why casting time is extended while you are wielded or if you
have less than 2 limbs.  Casting time is also affected by a number
of skills, such as quick chant and devil tongue.