Quick question about caster level and item creation [3.5]

[Land Outcast]

I might have been doing this wrong all along (that'd be some seven years).

Basically: can different spell effects on an item have different caster levels? Or are they all considered to be at the same caster level as the highest required?

[Calmar]

I think, they only need to be high enough to be cast in the first place.

[Land Outcast]

Yes, that's what I thought, but then I realized all items have a given caster level and the ones which do reproduce spell effects don't specify the caster level at which they are cast.

Until now I assumed it was "minimum necessary to cast each spell", but doubt struck.