A fractional unit of available space in a grid, and the code for French. A named abbreviation rather than a concept.
The CSS grid unit clips Latin fractio (a breaking, hence a fraction), while the same two letters serve as the ISO code for France, from Latin Francia; two unrelated histories sharing one written form.
A fractional share of available space in a grid, and, unrelated, the short code for France: one written shape carrying two separate histories.