SI derived unit m), the SI derived unit of density. The names of SI derived units, when written in full, are in lowercase. However, the symbols for units named after persons are written with an uppercase initial letter. For example, the symbol for hertz is "Hz"; but the symbol for metre is "m". The International System of Units assigns special names to 22 derived units, which includes two dimensionless derived units, the radian (rad) and the steradian (sr). Some other units such as the hour, litre, tonne, bar and electronvolt are not SI units, but are widely used in conjunction with SI units.
Hartley (unit) digit, a ban corresponds to a decimal digit. A deciban is one tenth of a ban; the name is formed from "ban" by the SI prefix "deci-". One hartley corresponds to log(10) bit = ln(10) nat, or approximately 3.322 Sh, or 2.303 nat. A deciban is about 0.332 Sh. Though not an SI unit, the hartley is part of the International System of Quantities, defined by International Standard IEC 80000-13 of the International Electrotechnical Commission. It is named after Ralph Hartley. The term "hartley" is named after Ralph Hartley, who suggested in 1928 to measure information using a logarithmic base