Unicode Explained

for use in new, originally Unicode data. The Unicode standard says, in the discussion

of unit symbols:

Unit Symbols. Several letterlike symbols are used to indicate units. In most cases, how-

ever, such as for SI units (Système International), the use of regular letters or other sym-

bols is preferred. U+2113 SCRIPT SMALL L is commonly used as a non-SI symbol for

the liter. Official SI usage prefers the regular lowercase letter l.

Three letterlike symbols have been given canonical equivalence to regular letters: U+2126

OHM SIGN, U+211A KELVIN SIGN, and U+211B ANGSTROM SIGN. In all three

instances the regular letter should be used. In normal use, it is better to represent degrees

Celsius “°C” with a sequence of U+00B0 DEGREE SIGN + U+0043 LATIN CAPITAL

LETTER C, rather than U+2103 DEGREE CELSIUS. For searching, treat these two se-

quences as identical.

Unfortunately, the Unicode standard has wrong information about the symbol for the

liter. The official position in the SI system is that both “l” and “L” are allowed, with no

expressed preference (although in the U.S., “L” is preferred by national authorities).

The special letterlike characters discussed here were taken into Unicode due to their

presence in some character codes used in East Asia, such as the Japanese JIS X 0212.

These characters do their job in allowing conversions between character codes without

losing information. Problems arise ...