Before a radio can do anything, it has to be told who it is and what it can reach. That configuration — the codeplug — is written with CPS (Customer Programming Software). You won't memorize a real one here, but you'll learn what each field is and why it matters, so the real CPS isn't a wall of mystery.
Field names and ID formats are from public P25 references and programming guides. Values shown are illustrative examples, not a real agency's plan. Real codeplugs, key assignments, and system IDs are controlled and come from your system administrator. This teaches the model, not a real radio's contents.