The above changes drive almost every other update in the document.
The official specification is a proprietary document managed by . Access depends on your membership status: PCI Express M.2 Specification Revision 5.0, Version 1.0 pci express m.2 specification revision 5.0 version 1.0 pdf
The physical "gold fingers" on an M.2 SSD have changed subtly. Rev 5.0 v1.0 revises the to reduce stub resonance. It also redefines the reference impedance from 85-ohm nominal to a tighter 85-ohm +/- 5% tolerance across the entire mating cycle. The above changes drive almost every other update
Even this updated specification retains known limitations: pci express m.2 specification revision 5.0 version 1.0 pdf
You may never open the 450-page PDF, but its contents affect your daily computing: