In “USBefuddled: Untangling the Rat’s Nest of USB-C Standards and Cables” (3 December 2021), Glenn Fleishman examined the hot mess of USB standards. But as Simon Baker at TFT Central points out, HDMI standards aren’t any better. The recent HDMI 2.1 certification adds many more display capabilities, like 8K resolution, 120 Hz refresh rate with 4K, and variable refresh rates. Unfortunately, it also does away with the HDMI 2.0 standard, incorporating it as a subset of HDMI 2.1. This means you could buy a display that claims to be HDMI 2.1-certified, but that actually supports only HDMI 2.0 capabilities. That could be a problem if you’re trying to buy a display to take advantage of high-end devices that support 4K resolution with 120 Hz refresh rates, like the new PlayStation 5 game console. Be careful and do your research before buying a display if you need HDMI 2.1-only features.