> So what does it even mean to comply with the spec then, if everything is optional? Similarly, I kept saying it for long that a file/wire format's usefulness

> So what does it even mean to comply with the spec then, if everything is optional? Similarly, I kept saying it for long that a file/wire format's usefulness is not in what it supports, but in what it forbids. A binary file supports any type of data, but it's not useful.