Ticket numbering: user page, developer guide, and the format-change question Three pages for GH discussion #71. Ticket-Numbering.md - every setting in the order the screen presents them, the tokens, why the digit width cannot run out, the renumbering tool and when it refuses. A section on multi-company installs answering the question that gets asked first: if company A gets TICKET-000001, does company B? No - and it CANNOT, because an email reply carries [SDREF:...] and nothing else, so a reference has to be unique across the install. That is why per-company counting requires {COMPANY} rather than it being a fussy validation rule. Changing-Ticket-Number-Format.md - the page for somebody who has been running for months and now wants a different scheme. It answers "is it OK to have old tickets on one scheme and new ones on another?" with yes, and argues that mixed is usually BETTER: nothing parses the shape, old tickets are mostly finished tickets, and the mixture tells you at a glance which era a reference is from. Renumbering earns its risk in one case - a fresh migration, before anyone is attached to a number - and the signals that it is the wrong choice are listed as plainly as the signals that it is right. Ticket-Numbering-Developer-Guide.md - the SDREF landmine and why the parser must stay format-agnostic; the claim/prove/jump loop and the two traps in claimNext; counter keys as the whole of what a "scope" is; why render() and counterKey() take an $at; NULL tenant meaning the DEFAULT company rather than none; plan/apply split so the destructive half is testable; and assertPlanSafe as the guard that checks what the plan CONTAINS rather than the causes anybody thought of. It also records the two failures this feature caused on a live install, because both are the kind that recur: a test suite writing to counter key 't' - which is production - and a ten-attempt collision loop that could not clear a counter that had fallen behind the estate. Sidebar updated under Tickets. Every internal link and every named source file verified to resolve.