Per mille (from Latin , "in each thousand") is an expression that means parts per thousand. Other recognised spellings include per mil, per mill, permil, permill, or permille. The associated sign is written , which looks like a percent sign with an extra zero or o in the divisor. The term occurs so rarely in English that major dictionaries do not agree on the spelling and some major dictionaries such as Macmillan do not even contain an entry. The term is more common in other European languages where it is used to express fractions smaller than 1%. One common usage is blood alcohol content, which is usually expressed as a percentage in English-speaking countries. Per mille should not be confused with parts per million (ppm). Computer systems The code point for the glyph is included in the General Punctuation block of Unicode characters: . It may be typed using , , , or according to operating system. Note that for the compose key sequence the percent key (%) is followed by lower case letter o and not, as might be expected, by digit 0. Examples Examples of use include: Legal limits of blood-alcohol content for driving a road vehicle in some countries: for example: 0.5‰ or 0.8‰. Seawater salinity: for example: "the average salinity is 35‰". Tunnel and railway gradients (in some countries in Europe). Birth and death rates. Baseball batting averages (colloquially). Property taxation rates: the millage rate (U.S.) or mill rate (Canada). Expressing stable-isotope ratios—for example: "δ13C was measured at −3.5‰". Fineness of precious metals. Cost per mille (CPM), the price of 1000 units, may be used for views of banner and display advertising, and for emails delivered by email service providers. Related units Percentage point difference of 1 part in 100 Percentage (%) 1 part in 100 Basis point (bp) difference of 1 part in 10,000 Permyriad (‱) 1 part in 10,000 Per cent mille (pcm) 1 part in 100,000 See also Parts-per notation Per-unit system Percent point function Fineness of precious metals (given as "0.000-fine") References External links 1000 (number) Typographical symbols