Acutally, Hold Person should not be an Enchantment/Charm spell, but an
evocation/invocation spell. Here is the reason.

A. It's an attack spell. It is used to hold one person in one place.

Just because a spell can be used for offense doesn't make it
invocation..the class a spell is in depends on how it works. THis
spell uses enchantment to make a humanoid does't call into
being something that was't there before, essentially out of nothing (as
I see Inv/Evoc spells working anyway)

B. It either pits a force to prevent the person from moving (eg.
gravity) or it
affects the voluntary nervous system (it prevents signals to be recieved
skeletal muscles). Either way, a force is invoked in both cases. I
prefer the
gravity effect, because Magic is an outside force.

Actually, you don't need to provide a force at all..the person simply
becomes incapable of moving...not lke paralysis, cause you'd fall to the
floor then, but the character is unable to move his/her muscles to
move..sort of convincing the brain that they don't work