The person in charge of administering our resources has taken to giving them a percentage participation in their main resource pool reflecting their available hours. This mostly works as our resources usually belong to one group.
I.e. 40h a week is 100% participation.
Half day resources have 50% participation
The remainder is allocated to non-workload capacity.
In addition to philip's post that you can set up ragion working hour 12 hours. In this way you can populate more possible working hour possibilities by resources participation percentage in resource pools
IT Governance Professional & PPM Solution Architect