I believe the problem here is that you will have PNG images that “look” like you can open them but can’t.
Labelling is a poor band-aid on the root problem - consumer cables which look identical and fit identically should work wherever they fit.
There should never have been a power-only spec for USB-C socket dimensions.
If a cable supports both power and data, it must fit in all sockets. If a cable supports only power it must not fit into a power and data socket. If a cable supports only data, it should not fit into a power and data socket.
It is possible to have designed the sockets under these constraints, with the caveat that they only go in one way. I feel that that would have been a better trade-off. Making them reversible means that you cannot have a design which enforces cable type.
That's even more confusing than the current state of affairs. If my phone has power and data socket, then I cannot use power only cable to only charge it? Presumably with the charger that has power only socket. So I need a cable with two different ends anyway. Just go micro-USB at this point :)
Funnily enough, there is a 100% overkill way to solve such issues. Just use super expensive certified TB cables. Well... plus a A-to-C adapter for noncompliant devices, I guess.
This is just pretending that if you have a cat and a dog in two bags and you call it “a bag”, it’s one and the same thing…
If PNG gets extended, it's entirely plausible that someone will view a PNG in their browser, save it, and then not be able to open the file they just saved.
There are those who claim "backwards compatibility" doesn't cover "how you use it" - but roughly none of the people who now have to deal with broken software care about such semantic arguments. It used to work, and now it doesn't.
It's a dichotomy. Either the provider accommodates users with older software or not. The file extension or internal headers don't change that reality.
Another example, new versions of PDF can adopt all the bells and whistles in the world but I will still be saving anything intended to be long lived as 1/a which means I don't get to use any of those features.
USB-C spec is anything but breaking backward compatible.
Do they mention which C libraries use this spec?
