How should I express a percentage in a message definition?

edit

So the recommendation is to use a 8 Byte variable to store a value that can fit into 1 Byte?

You are making assumptions in your assessment Humpelstilzchen. One byte is in general not sufficient. What about the representation of 37.7% or even 1/3%? float64 provides very good precision between 0.0 and 1.0, thus covering the majority of use cases vs something like a uint8.

You are now making the assumption that there are fractional. We don't know that since the questioner has not replied to my comment yet.

In my particular implementation, it is indeed fractional. But even if it wasn't, wouldn't we want the field type to be able to support a higher-precision value if we want a truly generalized and not implementation-specific message definition?

Still you are wasting a lot of bandwidth since float was not made to cover a small area, but a real large one. If you do not need human readable I would use an unsigned int and define 0% = 0 and 100% = max value.

You are now making the assumption that there are fractional

I was not actually, thank you. I was merely stating that, for the sake of generality, the choice of uint8 would be unwise and gave two examples. You are now at 4 bytes with your choice of unsigned int (uint32)... is that too much? too

little? If bandwidth is a concern then yes, go ahead and sacrifice readability, make assumptions, and make your own types (that is why such functionality exists) but I wouldn't expect any standard messages to follow suit unless it was in the nature of the underlying data.