Mikrotik-Recv-Limit-Gigawords and Mikrotik-Recv-Limit

Hi,
what are diffrences betwean Mikrotik-Recv-Limit-Gigawords and Mikrotik-Recv-Limit?

The total receive limit is an 64 bit (8 byte) number.
Mikrotik-Recv-Limit is the lower 32 bits (4 bytes) of the total limit.
Mikrotik-Recv-Limit-Gigawords is the upper 32 bits (4 bytes) of the total limit.

Total-Recv-Limit = Mikrotik-Recv-Limit + (Mikrotik-Recv-Limit-Gigawords << 32)