Variation Selector-90

It can request a registered glyph form for the character before it. VS90 is invisible and has no sound of its own. It belongs after a Han character—one used in Chinese and in some Japanese and Korean writing—in an ideographic variation sequence (IVS), a two-character sequence that records a registered glyph choice. The base character and VS90 together identify the form; “90” is not a general style setting.

Ideographic variation sequences address a typesetting problem: one written character can have historically or regionally preferred shapes, and plain text sometimes needs to preserve the chosen form across fonts. Proposals from 2003–2004 described these Han glyph differences and the need to register their pairs. Those proposals describe preserving writing choices, not when the forms themselves began.

Why does VS90 disappear or seem to do nothing?

It is invisible alone; a registered pair gives it its effect. VS90 is in the supplementary selector range used for ideographic variation, so its number does not map to a general look or font style. If a pair is unregistered or unsupported by the software, the base character displays normally and the selector stays invisible.