MRO (formerly MIRO) stands for Mass in Running Order, this is effectively the weight of the caravan or motorhome as it leaves the factory with no additions e.g. gas bottles.
MTPLM stands for the Maximum Technical Permissible Laden Mass (pre-1998 this was known as MGW maximum gross weight) this is the maximum weight a leisure vehicle can weigh inclusive of the user payload.
User Payload: If you take the MTPLM minus the MRO this will give you your user payload. This is the maximum weight that can be put inside your leisure vehicle when towing it or driving it.
