Editing Slash (punctuation) (section)

===Abbreviation <span class="anchor" id="Derived units"></span>===
The slash has become standard in several abbreviations. Generally, it is used to mark two-letter [[initialism]]s such as A/C (short for "air conditioner"), w/o ("without"), b/w ("black and white" or, less often, "between"), w/e ("whatever" or, less often, "weekend" or "week ending"), i/o ("[[input/output]]"), r/w ("read/write"), and n/a ("not applicable" or, in aviation, "not authorized"). Other initialisms employing the slash include w/ ("with") and w/r/t ("with regard to"). Such slashed abbreviations are somewhat more common in British English and were more common around the [[Second World War]] (as with "S/E" to mean "single-engined"). The abbreviation 24/7 (denoting 24 hours a day, 7 days a week) describes a business that is always open or unceasing activity.<ref name="solidhart" />

The slash in [[derived unit]]s such as m/s (meters per second) is not an abbreviation slash, but a straight division. It is however in that position read as 'per' rather than e.g. 'over', which can be seen as analogous to units whose symbols are pure abbreviations such as mph (miles per hour), although in abbreviations 'per' is 'p' or dropped entirely (psi, pounds per square inch) rather than a slash.<!-- Negative example because previous content erroneously claimed the opposite. -->

In the [[Government of the United States|US government]], the names of offices within various departments are abbreviated using slashes, starting with the larger office and following with its subdivisions. For example, the [[Federal Aviation Administration]]'s [[Office of Commercial Space Transportation]] is formally abbreviated FAA/AST.