Many people misunderstand how software is written in regulated industries, and assume that a standard is necessary. In practice, this is not the case. Note that Ferrocene[1] had to produce a specification[2] in order to qualify the compiler. But there isn't a requirement that it must be a standard in any way, only that it describes how the Ferrocene compiler works. Nor that it be accepted by upstream.
Exactly. I've heard so much "you must follow MISRA!" but MISRA is not actually the requirement - it's a solution that satisfies the requirement, and there can be other way to satisfy the requirement of your industry's regulations.