> When I treated headers as bytes, there wasn't an "encoding". oh, actually there was (either us-ascii or more likely iso-8859-1) the bytes are just values 0-2

> When I treated headers as bytes, there wasn't an "encoding". oh, actually there was (either us-ascii or more likely iso-8859-1) the bytes are just values 0-255 what these values mean is the encoding. You're confused because the encoding was implicit, rather than explicit. It would perhaps be clearer to see it if you for example had to chose if you use ASCII or legacy EBCDIC encoding.