Hartley (unit)
（重定向自Deciban）
The hartley (symbol Hart) is a unit of information defined by International Standard IEC 80000-13 of the International Electrotechnical Commission. One hartley is the information content of an event if the probability of that event occurring is 1/10. It is therefore equal to the information contained in one decimal digit (or dit), assuming a priori equiprobability of each possible value.