Editing Abbreviation (section)

=== Plural ===

There are multiple ways to pluralize an abbreviation. Sometimes this accomplished by adding an apostrophe and an ''s'' ({{char|'s}}), as in "two PC's have broken screens". But, some find this confusing since the notation can indicate [[possessive case]]. And, this style is deprecated by many style guides. For instance, [[Kate Turabian]], writing about style in academic writings,<ref name="Chicago">{{cite book|last=Turabian |first = Kate L.|title =[[A Manual for Writers of Research Papers, Theses, and Dissertations]] | edition = 7th | at=subsection 20.1.2| publisher = University of Chicago Press | author-link=Kate L. Turabian}}</ref> allows for an apostrophe to form plural acronyms "only when an abbreviation contains internal periods or both capital and lowercase letters". For example, "DVDs" and "URLs" and "Ph.D.'s", while the [[Modern Language Association]]<ref name="MLA">Modern Language Association (MLA) Handbook for Writers of Research Papers, 7th Edition 2009, subsection 3.2.7.g</ref> explicitly says, "do not use an apostrophe to form the plural of an abbreviation". Also, the [[American Psychological Association]] specifically says,<ref name="APA">Publication Manual of the American Psychological Association (APA), 5th Edition 2001, subsection 3.28</ref><ref name=autogenerated1>''Publication Manual of the American Psychological Association'', 6th Edition 2010, subsection 4.29</ref> "without an apostrophe".

However, the 1999 style guide for ''[[The New York Times]]'' states that the addition of an apostrophe is necessary when pluralizing all abbreviations, preferring "PC's, TV's and VCR's".<ref>Siegal, AM., Connolly, WG., [https://books.google.com/books?id=RT5w0s7_op8C&q=plurals+abbreviations ''The New York Times Manual of Style and Usage''], Three Rivers Press, 1999, p. 24.</ref>

Forming a plural of an initialization without an apostrophe can also be used for a number, or a letter. Examples:<ref>{{cite book|last=Garner|first=Bryan|title=Garner's Modern American Usage|year=2009|publisher=Oxford University Press|location=Oxford; New York|isbn=978-0-19-538275-4|page=638}}</ref>
* [[run batted in|Runs batted in]], RBIs
* The roaring 20s
* Mind your Ps and Qs

For units of measure, the same form is used for both singular and plural. Examples:

* 1&nbsp;lb or 20&nbsp;lb
* 1&nbsp;ft or 16&nbsp;ft
* 1&nbsp;min or 45&nbsp;min

When an abbreviation contains more than one period, ''Hart's Rules'' recommends putting the ''s'' after the final one. Examples:

* Ph.D.s
* M.Phil.s
* The d.t.s

However, the same plurals may be rendered less formally as:

* PhDs
* MPhils
* The DTs (This is the recommended form in the ''New Oxford Dictionary for Writers and Editors''.)

According to ''Hart's Rules'', an apostrophe may be used in rare cases where clarity calls for it, for example when letters or symbols are referred to as objects.
* The x's of the equation
* Dot the i's and cross the t's
However, the apostrophe can be dispensed with if the items are set in italics or quotes:
* The ''x''s of the equation
* Dot the 'i's and cross the 't's

In Latin, and continuing to the derivative forms in European languages as well as English, single-letter abbreviations had the plural being a doubling of the letter for note-taking. Most of these deal with writing and publishing. A few longer abbreviations use this as well.

{| class="wikitable"
|-
!Singular abbreviation
!Word/phrase
!Plural abbreviation
!Discipline
|-
|d.
| didot
|dd.
| typography
|-
|f.
| following line or page
|ff.
|notes
|-
|F.
| folio
|Ff.
|literature
|-
|h.
| hand
|hh.
| horse height
|-
|J.
| Justice
|JJ.
|law (job title)
|-
|l.
| line
|ll.
|notes
|-
|MS
| manuscript
|MSS
|notes
|-
|op.
| opus (plural: opera)
|opp.
|notes
|-
|p.
|page
|pp.
|notes
|-
|Q.
| quarto
|Qq.
|literature
|-
|s. (or [[§]])
|section
|ss. (or §§)
|notes
|-
|v.
|volume
|vv.
|notes
|}