Unifies integral eight-bit Octet with a list of Value:Width terms
where the Width integers sum to eight and the Value terms unify with
the shifted bit values encoded within the eight-bit byte.
- an eight-bit byte by another name.
- colon-separated value-width terms. The shifted value of
the bits comes first before the colon followed by its integer bit
width. The list of terms specify an octet by sub-spans of bits, or