Every complete, lawful set of navigation lights one vessel may show, from a fact record (propulsion, activity, position, length, and the other facts in colregs data/facts.json) under the COLREGS. Returns the applied entries, the entries exempted or excluded and by which entry, and lawful_displays: {count, relation, options}. relation is "none", "exactly_one" or "any_one_of". A fact record describes a situation, not a fitted vessel: colregs data/facts.json has no equipment fact, so nothing in the input can settle a choice the Rules leave to how the vessel is fitted or what the skipper elects, such as Rule 25(b), the combined masthead lantern a sailing vessel under 20 m may carry, against Rule 25(c), the all-round red over green she may add. When lawful_displays.count is greater than 1, every option is equally lawful, the correct report is all of them, and reporting any one as "the" display for this vessel is wrong. Each option numbers itself "n of count", names the choice entries that distinguish it (chosen) and lists its lights with their own modality, so "shall" and "may" lights in one display are never merged. optional_additions are lawful extras (relation any_subset_of) that do not multiply the display set. Every id carries its paragraph cite, and cited_paragraphs holds the verbatim text of every cited paragraph. Not for navigation. Coverage: COLREGS Part C lights only, international (high seas) text only, lights at night only (no day shapes, no sound signals, no Part B steering rules), evaluated against pre-release colregs data (0.x), whose content is still being checked. Every entry id and paragraph cite in a response is verbatim from the colregs data package; nothing is paraphrased. This tool surface is a 0.0.x preview and will change without notice.

The colregs applicability entries whose conditions hold for a fact record, as {id, cite} pairs in data order, without composing displays. Use evaluate_display for the lights; this is the cheaper question "which paragraphs speak to this vessel". Same input as evaluate_display. Not for navigation. Coverage: COLREGS Part C lights only, international (high seas) text only, lights at night only (no day shapes, no sound signals, no Part B steering rules), evaluated against pre-release colregs data (0.x), whose content is still being checked. Every entry id and paragraph cite in a response is verbatim from the colregs data package; nothing is paraphrased. This tool surface is a 0.0.x preview and will change without notice.

The verbatim text of a COLREGS paragraph from colregs data/rules.json, by its cite as used in every other response here: a paragraph path such as "25(b)" or "26(c)(i)", a bare rule number such as "25" for every paragraph of that rule, or a range such as "24(a)(ii)-(iv)". The text is the International text as transcribed from the USCG amalgamated Navigation Rules; the response names the source and retrieval date. Not for navigation. Coverage: COLREGS Part C lights only, international (high seas) text only, lights at night only (no day shapes, no sound signals, no Part B steering rules), evaluated against pre-release colregs data (0.x), whose content is still being checked. Every entry id and paragraph cite in a response is verbatim from the colregs data package; nothing is paraphrased. This tool surface is a 0.0.x preview and will change without notice.

The definition of one light from colregs data/lights.json, verbatim: name, the Rule 21 paragraph that defines it, colour, character, arc in degrees and placement. Ids are the light ids that evaluate_display returns, such as "light:sidelights" or "light:all_round"; the "light:" prefix is optional. Arcs use the bearing convention returned alongside. Not for navigation. Coverage: COLREGS Part C lights only, international (high seas) text only, lights at night only (no day shapes, no sound signals, no Part B steering rules), evaluated against pre-release colregs data (0.x), whose content is still being checked. Every entry id and paragraph cite in a response is verbatim from the colregs data package; nothing is paraphrased. This tool surface is a 0.0.x preview and will change without notice.