The field reference, layer by layer.

Every standard in this reference exists because something in space went wrong — a frame lost in noise, a command that arrived twice, a link that vanished mid-pass — until someone designed the failure away. Each entry explains a protocol from that starting point: the situation that demanded it, not the section numbering of its spec.

The goal is intuition. A specification tells you what the fields are; these pages try to tell you why the fields exist — what each protocol protects, what it costs, and what breaks without it. After reading an entry, the spec should feel less like a wall of rules and more like the only shape the solution could have taken.

Most flying missions speak a blend. CCSDS dominates the framing and packet layers; ECSS prescribes the engineering practice around them; IETF owns the delay-tolerant parts that look Internet-shaped. The protocol stack is OSI-shaped but not OSI — a working model, not a theory.

Each entry stands alone — read it when a spec lands on your desk, or browse the stack layer by layer below. The reference is being written serially, so many pages currently hold a place rather than a text; the index is the full map of where it is headed. And when you want the longer story around a standard, the entry links to the Primer chapter where it first appears.