A variety of different styles may be used for formal invitations. The following style should be used in all other print and electronic communications.
For dates, use 1, 2, 3, 4, not 1st, 2nd, 3rd, 4th. Write "Reservations are due July 27," not "Reservations are due July 27th."
Abbreviations
Do not abbreviate days of the week.
Do not abbreviate months of the year when they appear by themselves or with a year (December 2012). March, April, May, June and July are never abbreviated in text, but the remaining months are when they are followed by a date (Jan. 27), and are correctly abbreviated Jan., Feb., Aug., Sept., Oct., Nov., Dec.
Correct
The semester begins in September.
The semester begins in September 2012.
The semester begins Sept. 4.
The semester begins Tuesday, Sept. 4.
The semester begins Tuesday, Sept. 4, 2012.
If only the month and year are used, do not use commas. Do not use the word "of" between the month and the year.
Use: We met in December 2011 (not December of 2011).
Appositives and phrases introduced by a comma must always be closed by a comma (or period at the end of a sentence).
Use: The meeting was held Tuesday, Sept. 19, at the Fetzer Center.
Note the commas preceding and following Sept. 19.
Use:They were married May 14, 2012, in Chicago.
Note the commas preceding and following 2012.
Be concise and consistent
When to include the year
Include the year only if it is different from the present year (the year in which the publication or correspondence is dated) and always if the year is different from the present year.
Avoid using "last" and "next"
Last has several meanings and its use in reference to time can be confusing. The phrase "during the last month" can mean either "during the previous month" or "during the final month." Previous, past, and final have more specific meanings and should be used in place of last. Similarly, the word next also can be confusing and should be avoided.
Make your meaning clear
A week can be defined as a specific seven-day period or as any seven consecutive days. A month can be defined as a specific month of the calendar or as any period of 30 consecutive days. A year can be defined as a specific calendar year or fiscal year or as any period of 365 consecutive days.
If you write, "During the past year, the University raised $17.5 million," do you mean during the previous calendar year, or during the previous fiscal year, or during the 365 days immediately preceding the date of your writing? If you write "During 2011," or "During the 2011-12 fiscal year," or "During the past 12 months," or "From April 2011 through March 2012," the period covered is more clearly defined.
Fiscal and academic years
For academic and fiscal years, use 2011-12, not 2011-2012. The single exception to this rule is at the end of a century, for example, 1999-2000.
Decades
For decades, use 1960s, 1990s or use '60s, '90s (no apostrophe before the s).