Quotation mark
Straight quotation marks (or italicized straight quotation marks) are often used to approximate the prime and double prime. For example, when signifying feet and inches, arcminutes and arcseconds, or minutes and seconds, where the quotation mark symbolises the latter part of the pair. For instance, 5 feet and 6 inches is often written 5' 6", and 40 degrees, 20 arcminutes and 50 arcseconds is written 40° 20' 50". When available, however, the prime should be used instead (e. g., 5′ 6″, and 40° 20′ 50″). Prime and double prime are not present in most character sets, including ASCII and Latin-1, but are present in Unicode, as characters U+2032 (dec. 8242) and U+2033 (dec. 8243), and as HTML entities &prime; and &Prime;. Double quotation marks are also often used to represent the ditto mark.