While the base architectural specification defines the electrical behavior, the CEM specification defines the physical slot and connector.
Note: As of current timelines, PCIe 6.0 (released in 2022) is the successor, utilizing PAM-4 encoding to hit 64 GT/s, but PCIe 5.0 remains the current industry standard for high-end consumer and enterprise hardware.
Pcie 5.0 Specification [updated]
While the base architectural specification defines the electrical behavior, the CEM specification defines the physical slot and connector.
Note: As of current timelines, PCIe 6.0 (released in 2022) is the successor, utilizing PAM-4 encoding to hit 64 GT/s, but PCIe 5.0 remains the current industry standard for high-end consumer and enterprise hardware. pcie 5.0 specification