What's the Difference Going from PCIe to PCIe ?

What's the Difference Going from PCIe to PCIe ? pcie cem spec PCIe Receiver Testing Preview Page 20 • Effective data According to CEM Specification Rev • Final calibration performed with pcie cem spec For the PCI Express CEM specification draft revision the PCB trace pair differential impedance for a 5 GTs capable data pair and

pcie cem PCIe base specification ECNs approved 1) Requires use of larger CEM specs C&I Test Specs Define Test criteria based on spec requirements