This order can be disabled for use by rulevar 507

Only a unit with passengers onboard can unload.

Only a passenger unit with more then 0 AP can be unloaded. Unless you are attempting to unload while the cargo ship is in a port.

You can unload a unit in the harbour hex the naval unit is present in or if the naval unit is at sea at any neighbouring land hex with a landscape type that support amphibious landings.

If your attempting to take enemy territory the unit needs at least rulevar 307 power points.

There may not be more then 15 units already gathered in the target hex if the target hex is friendly.

If enemy units are present combat can be initiated.

The script in rulevar 843 will be called.