[userbinator]

Define non-malleable encodings; in other words, ensure that there exists only one valid encoding for any valid message, eliminating parser bugs that emerge around handling (or not) multiple different ways to encode the same thing.

I've said similar things to this before. E.g. if you want a boolean, there's nothing simpler and less error-prone than a single bit. It represents exactly the values you need; nothing more and nothing less. You could take a byte if you didn't want to pack, and use the "0 is false, nonzero is true" convention, which is naturally usable in a lot of programming languages; that way there are 256 different values, but the set of inputs is still small and finite with each one having a defined interpretation.