A figure space is a typographic unit equal to the size of a single typographic figure (numeral or letter), minus leading. Its size can fluctuate somewhat depending on which font is being used. This is the preferred space to use in numbers. It has the same width as a digit and keeps the number together for the purpose of line breaking.
In Unicode it is assigned U+2007 FIGURE SPACE (HTML
- Heninger, Andy, ed. (2013-01-25). "Unicode Line Breaking Algorithm" (PDF). Technical Reports. Annex #14 (Proposed Update Unicode Standard): 19. Retrieved 10 March 2015.
WORD JOINER should be used if the intent is to merely prevent a line break
- Fischer, Eric. "The Evolution of Character Codes, 1874-1968" (PDF).