So, cables shouldn't have a wire on pin 20. This means that you could have a dongle (say, a DP-to-VGA converter) that works when plugged into the source, but d

So, cables shouldn't have a wire on pin 20. This means that you could have a dongle (say, a DP-to-VGA converter) that works when plugged into the source, but doesn't work when plugged into a cable and a gender-changer to effectively form an extension cable. I'd argue, therefore, that extension cables (purpose-built with M-to-F connectors) should wire pin 20, and only M-M cables should omit it.