A check mark in this field indicates that the program, when calculating the need for replenishment orders, will include inventory in the projected available balance.
The field contains a check mark as a default setting and is also non-editable, since it is normal practice to use inventory to fulfill outstanding requirements.
The only exception is if you select the reordering policy Lot-for-Lot. The field will still contain a check mark as a default setting, however it will be editable.