What ⬌ means
A route or relation can run each way.
Early map and diagram arrows resembled an archer’s arrow. In 1737, French engineer Bernard Forest de Bélidor used one to show water flow and a waterwheel’s rotation.
Mathematician David Hilbert used an arrow for implication—one statement follows from another—in 1922. A decade later, double-headed arrows marked logical equivalence: each statement implied the other. ⬌ joined Unicode in 2003 through a compatibility proposal for North Korea’s KPS 9566 character standard. In 2014, Unicode harmonized the black-arrow family with the Wingdings and Webdings symbol fonts.
Don't confuse it with
2Questions people ask
1Why does ⬌ vary across fonts?
Fonts can give black arrows different weights and proportions; the underlying character stays the same.
How to type ⬌
⬌\2B0CCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.