Government Procurement Act Article 21

In order to apply the selective tendering procedures, an entity may conduct qualification review in advance and establish a permanent list of qualified suppliers; provided, however, that the entity shall always allow suppliers to request of qualification review and periodically review and update the permanent list of qualified suppliers.Where a supplier not on the permanent list of qualified suppliers requests to participate in a particular procurement, the entity shall review the qualification of such supplier provided that the review does not interfere the tendering procedures and can be completed in time. After reviewing, the entity shall invite such supplier to participate in the procurement provided that the supplier is qualified.The permanent list of qualified suppliers adopted for the procurement in connection with recurring demands shall contain at least six suppliers.In conducting selective tendering procedures, the entity shall give qualified suppliers an equal opportunity to be invited.