Unicode Explained

• The division symbol used for constructing derived units like “m/s” (meters per

second) is most logically identified with the division slash U+2215. However, this

character is not present in most fonts, so it is normal to use the ASCII solidus

U+002F, also known as slash, character as surrogate. In theory, division slash

would be preferable, since it has a more exact meaning.

• The minus sign used before a number (in an exponent, too), is logically to be

identified with the minus sign, U+2212. However, instead of this character, the en

dash, U+2013, or (far more often) the ASCII hyphen-minus U+002D is used. A

problem with these is that Unicode line breaking rules permit a line break after

these characters. This creates the risk of having the sign appear at the end of a line

and the number at the start of the next line. (This should not happen for the real

minus sign.) There are various ways to try to avoid this problem—e.g., by using

the nonstandard nobr markup in HTML authoring.

• The space between a numeric value and a unit (or between unit symbols when

multiplication of units is indicated in this less satisfactory way). It is difficult to say

how the space is to be interpreted in Unicode, considering the multitude of space

characters in Unicode. Presumably, any space character, excluding those with zero

width, is acceptable. Using the no-break space U+00A0 character would help in

preventing ...