linear programming

I have a question in context of linear programming. Please say whether these statements are correct.

1) Slack is where there is a spare capacity. Limited resources available has not been fully utilised in optimal production plan.

For eg if we have 100 kg of material available but we have used only 60 kg then slack is 40 kg because we didn’t use all the material.

2) Binding is where there is no spare capacity. Limited resources available has been fully used in optimal production plan.

For eg if we have 100 hours of labour available but we have worked 100 hours then slack is 0 and binding because we have used all the labour hours.

3) Surplus is where there is no more limited resource available. Limited resources are not sufficient to produce optimal production plan.

For eg if we have 100 kg of material available but our optimal production plan requires 120 kg then optimal plan cannot be achieved because we don’t have enough materials.

Thanks in advance for your help. You always answer I appreciate that 🙂