Quick answer
Oscar is the flag for the letter O. Flown as a single-letter International Code signal, it means “Man overboard”. It has yellow and red diagonal halves. The meaning given here applies to the single-letter signal; combinations must be read using the Code. See International Code of Signals, Pub. 102.
| Feature | Description | Evidence level |
|---|---|---|
| Letter and spelling word | O — Oscar | Official Code spelling table |
| Single-letter meaning | Man overboard | Official Code signal meaning |
| Design | Yellow and red diagonal halves | Identification pattern in official signal references |
| Proportions | No universal numerical ratio established here | Illustrations are not treated as dimensional specifications |
| Physical colours | Yellow and red; no exact textile colour standard established here | Colour names do not establish Pantone, dye or colorimetric values |
| Manufacture | No common manufacturing ratio, fabric or seam allowance established here | No manufacturing standard reviewed |
| Screen colours | No HEX or RGB values specified | A screen rendering would be an approximation |
Construction and artwork
The official references support identification by yellow and red diagonal halves. They are not used here to derive numerical dimensions, colour coordinates or manufacturing tolerances. A measured construction drawing would need a separately identified specification; a drawing made without one should be labelled an editorial reconstruction.
The Singapore port reference provides an official identification chart, rather than a textile manufacturing specification.
History and present status
The revised International Code was adopted on 27 September 1965 through Resolution A.80(IV). That resolution proposed 1 January 1968 for implementation subject to conditions; it should not be read as evidence of unconditional commencement on that date.
The preface to U.S. Publication 102 states that the 1969 edition became effective on 1 April 1969. These dates concern the revised Code, not the first appearance of Oscar’s design or meaning.
The IMO publication description states that the Code has not been amended since its fourth edition, published in 2005, and that the current edition contains minor editorial improvements. Oscar is treated here as a current maritime signal, not a historical national flag.
Sources
- International Code of Signals, U.S. Publication 102: flag chart, spelling table, single-letter signals and preface.
- Singapore port information: International Code of Signals identification chart and single-letter meanings, updated 14 November 2024.
- Resolution A.80(IV), adopted 27 September 1965: adoption and conditional implementation provisions.
- IMO e-Publications: International Code of Signals edition and amendment history.