USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB
What's optional?<p>That's the most important thing to know is what's optional in the spec.<p>That could make it great or a major pain. I'm referring to how many features the specification defines as "optional" for manufactures and that the USB organization requires for logos.<p>This is why even USB-C is a nightmare.  Consider a USB-C cable or device port. It could be charge only, data only, monitor support.  There are even more permutations and sub-features. Oh, you wanted charging and found one that has it?  Know how much power it enough or overkill? It could provide 15 watts, 100 watt, etc.  Think you'll just google the specs page? Sure, they never miss providing any of these details or make any mistakes.<p>Whether USB4 means one thing with nothing optional (or at least a very small number of combinations), will probably determine how much you like it or get annoyed by it.<p>HP even made it worse with a laptop USB-C port that could technically be used for certain docking functionality but tried to fud-deny allowing it for marketing reasons.