1.03 Periods

In recent years there has been a trend toward the omission of periods in abbreviations. This is particularly true of scientific and technical writing, but the practice has been spreading in general writing as well.

(a) Do not use periods with the following:

• chemical symbols and mathematical abbreviations: H₂O, NaCl, cos, log, tan;
• SI symbols and units: cm, kg, L (see 1.23 The International System of Units);
• abbreviations for points of the compass, except with street addresses (winds NNW but King St., Street E.);
• the military rank abbreviations used in the Department of National Defence (see 1.07 Military abbreviations);
• short forms of words: lab, flu, vet, stereo, typo; abbreviations or acronyms consisting exclusively of upper-case letters or ending in an upper-case letter (except those for personal names, legal references and most place names), e.g. NAFTA, PhD, YMCA, UN, GST, MiG, CTV.

(b) Use periods

• with geographical abbreviations, e.g. B.C., P.E.I., but not for the two-character symbols recommended by Canada Post (see 1.09 Geographical names).
• with most lower-case abbreviations, including a.m., p.m., e.g., i.e. (mph is one of the few exceptions).
• at the end of abbreviations for single words: Mr., Jr., Ltd., misc., pp., Nos.
• after each abbreviated word of a multiword term or phrase, where the abbreviation of each word consists of more than single initials, e.g. Rev. ed., Rt. Rev. (space required after each element in the abbreviation).
• after initials in a person’s name:
  • Thelonius S. Monk
  • H. E. Hughes
    (space required between each period and the following initial or name)

Periods, Note

If a sentence ends in an abbreviation taking a period, only one period is used.

For further information on spacing, see 7.02 Spacing.

1.04 Plurals

Add an s, but not an apostrophe, to form the plural of most abbreviations:

• ADMs
• BMWs
• CAs
• CRs
• FTEs
• GICs
• MPs
• PCBs
• 747s

Use an apostrophe and s to form the plural of numerical names of aircraft ending in a single letter:

• 727-100C’s
• 747B’s
• Cessna 402B’s

In cases where the resulting form would be ambiguous, add an apostrophe before the s:

• c.o.d.’s
• Q’s and A’s
• SIN’s

Add an apostrophe and s to form the plural of abbreviations containing more than one period, and an s without an apostrophe, to form the plural of abbreviations with only one period. In the latter case, the s precedes the period:

• G.M.’s
• Gens.
• pts.

The plurals of Mr. and Mrs. are irregular:

• Mr.
  • Messrs.
• Mrs.
  • Mmes.

The plural forms of the abbreviations for certain bibliographic references are different:

• l. (line)
  • ll. (lines)
• p. (page)
  • pp. (pages)
• f. (and the one following)
  • ff. (and those following)
• c., ch. (chapter)
  • c., ch. (chapters)
• MS (manuscript)
  • MSS (manuscripts)
• s. (section)
  • ss. (sections)
• subs. (subsection)
  • subss. (subsections)

Note that SI/metric symbols maintain the same form for both singular and plural and are written without periods, except at the end of a sentence:

• 1 cm
• 5 cm, centimetres
• 75 kg, kilograms
• The boxer weighed only 75 kg, kilograms.

1.06 Titles used with personal names

Use the following abbreviations for non-military titles preceding or following personal names:

1.06-1

• Dr.
• Esq.
• Hon.
• Jr.
• Mr.
• Mrs.
• Ms.
• Messrs.
• Mmes.
• Msgr.
• Prof.
• Rev.
• Rt. Hon.
• Sr.
• St.

Use Ms. when referring to a woman unless a preference for Mrs. has been indicated. Although not an abbreviation, Ms. is written with a period, by analogy with Mr. and Mrs. Note that Miss is not an abbreviation and does not take a period.

Do not use Mr., Mrs., Ms., Dr. or Esq. with any other abbreviated title or with an abbreviation denoting an academic degree or honour:

• Dr. Roberta Bondar or Roberta Bondar, MD

not

• Ms. or Dr. Roberta Bondar, MD

• Mr. Paul Kelly or Paul Kelly, Esq.

not

• Mr. Paul Kelly, Esq.

Do not use the abbreviation Dr. and Rev. Dr. before the names of individuals who hold only honorary doctorates.

Saint is written out for names of persons revered as holy, but may be abbreviated in informal contexts and in lists and tables:

• Saint Catherine
• Saint Francis of Assisi
• Saint Peter
• Saint Theresa

St. and SS. (plural) are the abbreviations used.

Abbreviate professional and official titles only when they are used with surnames preceded by first names or initials:

• Gen. Lewis MacKenzie but General MacKenzie
• Dr. Irene Taguchi but Doctor Taguchi
• Prof. A. N. Chomsky but Professor Chomsky

Note that there are spaces between each period and the following initial or name.

Even when used to address someone in correspondence, Rt. Hon., Hon. and Rev. must be preceded by the:

• The Rt. Hon. Jean Chrétien, Prime Minister of Canada
• The Hon. Alfonso Gagliano, Minister of Public Works and Government Services
• The Rev. John Smith

Titles used with personal names, Note

The honorary title "the Honourable" is used before the names of members of the Canadian Privy Council, lieutenant-governors and certain other officials. The title "the Right Honourable" applies for life to the governor general, prime minister and chief justice of Canada. See Department of Canadian Heritage, Precedence of Canadian Dignitaries and Officials.

Do not abbreviate Mayor, Vice-President, Professor and Father when used with personal names.

10.17 Salutation or greeting

The salutation will vary depending upon the person addressed and the nature of the letter. The following are some appropriate salutations for various circumstances:

• Sir or Dear Sir
  Madam or Dear Madam
  (for formal correspondence)
• Dear Mr. or Mrs.
  or Ms. Jones
  (for a more personal letter)
• Dear S. Jones
  (if sex of recipient is not known)
• Dear Sir/Madam
  Dear Sir or Madam
  (where a title is used but the
  person’s name is not known)

If the person’s name or title is not known, the expression To whom it may concern may also be used. It is not recommended that Mr., Mrs. or Ms. be used with a title as a salutation, as in "Mr. Premier."

The salutation begins at the left margin. For capitalization in a salutation, see 4.35 The salutation and complimentary close; for punctuation, see 7.27 The Colon, Miscellaneous.

14.02 Elimination of Sexual Stereotyping, Correspondence; names and forms of address

The form preferred or used by the person being addressed or referred to should be retained if it is known. Otherwise, the following guidelines should be applied in order to ensure uniform and equal treatment of the sexes.

• In formal correspondence, use Ms., Mrs., Miss or Mr. When the addressee is a woman, and her preference cannot be ascertained, use Ms.:

  Dear Ms. Samuels:

• If the gender of the addressee is not known, begin your reply with "Dear" followed by the person’s initials and surname:

  Dear J. D. Simmonds:

  Where the name of the addressee is not known, use the form "Dear Sir/Madam" or "Dear Madam or Sir."

• When writing to an organization or to unspecified individuals, use an inclusive salutation:

  Dear Members of the Rotary Club:
  To the Consumer Relations Department:
  To whom it may concern:

An alternative is to use the memo format and omit the salutation.

See also 10.17 Salutation or greeting.

© Travaux publics et Services gouvernementaux Canada, 2013
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