X Forum manages specifications, test suites, lab selection, certification issuance, and registry of certified products. However, to keep impartiality it does not get involved in testing. Vendors primarily work with the WFDCL of their choice that accepts the certification application, conducts the tests, and, if tests are successful, issues a certification certificate. The certification process starts ahead of the equipment submission process with plugfests. Although plugfests are optional they can provide valuable insights into the certification process. This enables vendors to address any issues that would otherwise emerge later during certification testing, and could delay certification. Participation in plugfests is public, but the WiMAX Forum, test labs, and participating vendors are required to keep the testing results confidential. Figure 4.20 shows the certification process which formally starts with equipment submission and lab selection. The vendor also can choose whether the submitted product should be treated as a device or as a module that will be added to multiple devices, and whether it is an upgraded version of a previously certified product or a product with a previously certified WiMAX module. At this stage, the vendor has to submit the Protocol Implementation Conformance Statement (PICS), which affirms that the vendor supports all the capability to be tested during the certification process and that the product meets the certification requirements. The testing lab will also require the submission of a Protocol Implementation Extra Information for Testing (PIXIT) document that provides information on the equipment configuration, plus additional information on the product. In the next step all the six certification modules are verified. If any test fails, the certification testing is halted and the vendor is asked to make the needed changes and to restart the certification process. If all tests are completed successfully, the WiMAX Certification Body (WCB) reviews the results and acknowledges the 