USB4 Specification v2.0
What does the &quot;4&quot; in USB4 mean? When does it change? Why did it change fairly frequently until recently (with minor versions like 3.1), but then stop at 4?<p>I had always assumed the number in the name was the spec version. But now the spec version is explicitly v2.0, but the &quot;4&quot; remains in the name. Why isn&#x27;t this USB5.0?<p>It&#x27;s not like USB ports are labelled with what USB version they support or anything, such that there would be valid reasons to have a &quot;compatibility version&quot; that stays at 4. USB ports are just labelled&#x2F;colored according to a marketing term that loosely maps to supported link speed (Hi-Speed &#x2F; black, Super-Speed &#x2F; blue, etc.)<p>Is this a thing like X11 (the &quot;11&quot; was a protocol version number once upon a time!), where the major version in the name somehow gradually ossified and became hard to change, even as major things kept happening to the spec; and so they just gave up and made the version an opaque part of the name, and lifted the version out somewhere else?