ETO Project Commitments Question

I need to better understand ETO project commitments.  Document "Understanding P31P001 Project Inventory Commitments (Doc ID 1263454.1)" states that "The project work order parts list will hard commit available inventory on a project by project basis.  This means that inventory committed to one project is unavailable to commit or issue to another project." and also, "The hard commit flag is a hidden field in the P3111 parts list file F3111.  In addition, project specific item commitment records will be created in the F410211.  These records are used to prevent the commitment or issue of available inventory except to the assigned project."