Comment 4 for bug 921866

In other ERP's generated MRP orders are with a new MRP run deleted and regenerated based on the new situation.
These orders are called "Planned Orders" and have that status in the system, so they are easily detectable.

When a planner is working on a "Planned Order" he can set the order in status "Firm Planned" and MRP will not affect the order.
If planner has finished his work on the order the status will change to confirmed and virtual stock will be affected.

Concluding that virtual stock is functional misused as Kyle did report.
the way to go for MRP calculation should be:
1. Delete all "Planned Orders" for the calculated item.
2. Calculated what should be ordered. Take current Firm Planned orders into this calculation.

planned order =
A suggested production, purchase or replenishment order generated by an MRP or other planning system to meet a projected shortage against desired safety stock levels. The shortage date becomes the due date, the release date is backward scheduled based on lead time, and the quantity is based on the specified lot size. Planned orders for upper level items create requirements for lower level components, and MRP generations delete existing planned orders and regenerate new ones based on changes in requirements. Planned orders must be firmed or accepted before releasing to production or to a vendor.

 jm2c