The WTO Agreement on Government Procurement (GPA) is a "plurilateral" agreement, which means that it applies to a number of WTO Members, but not all Members. The GPA's membership is limited to the 40 WTO Members that specifically signed the GPA or that have subsequently acceded to the Agreement. WTO Members are not required to join the GPA, but the United States strongly encourages all WTO Members to participate in this agreement. Several countries, including China, Jordan, and Moldova, are currently negotiating accession to the GPA.