Check & Cross

yes / no, and not everywhere

Unicode: U+2713 check mark · U+2717 ballot x · U+2611 ballot box with check · U+25CB white circle
The job: Mark one item as chosen, correct or complete and another as rejected or wrong — instantly, without words, and legibly at sixteen pixels, in one ink, on a photocopy.
Standards: Effectively none — and that is the entry. The most-used affirmation pair in the world rests on no standards number, unlike ⚠ (ISO 7010) or ⏻ (IEC 60417). It spread by convention alone and was ratified only after the fact, by being encoded.
Failure modes: At small sizes the pair differs mainly by whether two strokes cross, so the distinction dies before the glyph does. Encoding the pair by colour alone fails for the commonest colour-vision deficiency. And one glyph carries two grammars: a check inside a box means selected, a check beside an item means done — a state and an event wearing the same mark.
Cultural flips: The checkbox is not universal. In Japanese marking convention the affirmative is ○ maru, the negative × batsu, with △ for partial credit and ◎ ranking above ○. The tick is not the yes-mark in that system; it reads as “looked at” at best. An interface that ships a check as self-evidently affirmative has assumed a convention, not used a universal.

Sources · 4

documented The Unicode Standard: U+2713 CHECK MARK, U+2717 BALLOT X, U+2611 BALLOT BOX WITH CHECK, U+25CB WHITE CIRCLE.
documented ISO 7010 registers safety signs by shape and colour and assigns the affirmation pair no place in that grammar — a verifiable absence, and the point of the field.
traditional The ○ / × / △ / ◎ marking convention: universally taught and used in Japan, and to this Institute’s knowledge not fixed by any published standard. Sourcing this properly is an open task.
folk “A tick means wrong in Japan.” Widely repeated in design writing. What is defensible is weaker and more interesting: the tick is simply not the affirmative mark there, and its reading is unstable rather than inverted.