Inferred can be used in a study at PFS and BFS level but can't...

Inferred can be used in a study at PFS and BFS level but can't be declared as part of the ore reserve.

It is not good form to schedule a significant amount of inferred resource within the payback period, indeed it's best left to the end of the mining schedule. In an open pit this is what generally happens because it's the ore on the extremities of the pit and the last to be mined.

It is also poor form to use inferred resources in the determination of the pit size. Measured and indicated resources are used to determine the pit size and any inferred within that pit can be included in the schedule. A prudent approach would be to assess the impact of the scheduled inferred resources on the project value. If the impact is significant (>10%?) then factor down the tonnes of inferred in recognition of the uncertainty which attaches to that category of resource.