Variation Selector-166

In a valid pair, it requests one particular character form. An ideographic variation sequence (IVS) places the selector after an ideograph, a character used in Chinese, Japanese, and related writing. The earlier character is the base; the selector requests a registered glyph, or visible form. The Ideographic Variation Database (IVD) groups such pairs into collections; some preserve forms used in personal and place names.

Unicode encoded VS166 in 2003. That dates the digital character, not the older typographic need to specify a glyph form in plain text.

Why does VS166 look blank?

A variation selector normally has no visible mark of its own. It affects the preceding base only in a supported pair. If a pair is invalid or unsupported, the base normally stays visible and the selector contributes no visible mark.

Two strings can look alike while their code points differ. Some search, sorting, or parsing tools ignore selectors like this, while code-aware software can still distinguish the strings.

What if someone sends VS166 alone?

Alone, it has no base to modify or message of its own. It is an invisible formatting mark, so its presence by itself gives no separate reading or reason to infer the sender's intent.