A category declares its own questions, and the answer to a numeric one is stored as a number as well as text — which is the only reason a reader can ask for cars under a hundred thousand kilometres. You add categories and their questions yourself; nothing here is fixed in the program.

Published, not past its date, and its category still in use. All three, in one place, so the list, the category page, the advertisement's own address and the sitemap can never disagree about whether something is still showing.

When a poster asks for his number not to be shown, it is not merely left undrawn — it never leaves the server. A number sent to a browser is a number a scraper already has.