What are (C) mintage coins?

What does c mintage mean? I bought a set of QEII 2022 coind sold as mint uncirculated. Should I record  them under the regular mintage, uncirculated or under this  (C) mintage uncirculated. It seems odd to me that people would have paid more for the regular uncirculated then a mint of circulated.

It means that the number of the circulation coins also includes the set coins, it's just a shorthand not to repeat ‘mintage included in' all the time.

Thanks!