[gaius]

Trying to infer an injustice by the what the check is called has no point.

Sure it does. Ever seen a contract that promises a bonus of “up to” some percentage? That should be read as “no matter how well we do your upside is capped and management trouser the rest”. It's a calculated, deliberate strategy to exploit naivety.

[WalterBright]

Again, it's the amount on the check that matters, not what the check is called.

Seriously, if you believe you're delivering far more value than what your checks represent, it's time to have a chat with the boss and go over it. If there's still no agreement, find another job.