Subpart 51.1 of the Federal Acquisition Regulation (FAR), Contractor Use of Government Supply Sources, prescribes the policies and procedures under which federal contractors can use government supply sources, like GSA Schedule Contracts, to facilitate the completion of their contract. Traditionally, this allowance only enabled Prime contractors to purchase certain supplies and services not requiring a statement of work if they were on a Cost Reimbursement Contract. In 2009, GSA established a deviation to FAR 51.1 that allowed contractors to purchase from other contractors under both Cost Reimbursement and Time & Materials Contracts.