This article resembles two different ways of designing protocols. In tcp [0], information are encoded in position, e.g. the first 16 bits are for source port and the next 16 bits are for dst ports. While in, say, FIX [1], information are encoding be delimiters and position doesn't matter.

[0] https://en.wikipedia.org/wiki/Transmission_Control_Protocol

[1] https://en.wikipedia.org/wiki/Financial_Information_eXchange