Right, and in data transfer every byte can be placed in an absolute order relative to every other. And the digits within the respective fields are already big-endian (most significant digit first), so making the fields within the whole date little-endian is mixed-endian.
I have iterated this several times, so I worry there’s a fundamental miscommunication happening here.
Ok, I think I see the problem. To me, MSb (Most Significant bit) isn’t an ordering at all, just a label that one particular bit has. To specify an ordering, you’d also need to say whether that bit comes first or last. This concept doesn’t exist in computer memory because, as previously mentioned, bits in a byte aren’t ordered in memory. I was thinking of the individual digits in a field (each Y in YYYY) as separate bytes in a word, so endianness order makes sense to think about; separate fields in this analogy were contiguous like struct fields. I think my mental model is sensible, since ISO 8601 is fundamentally a sequence of characters, which are all in an absolute order.