Accurate representation of eras, centuries, dates, decades, months, times of day and seasons

AD, BC/ CE, BCE

1. The terms AD or anno Domini, “in the year of the lord,” and BC, “before Christ,” stand for calendar periods in the “Christian Era.” Traditionally, year one or AD 1 is reckoned as the year of Jesus’ birth, and 1 BC stands for the first year prior to his birth. The terms CE, “common era,” and BCE, “before the common era,” are used to represent the same dating system for those who don’t wish to identify time periods with Christianity. Users of this style guide are encouraged to use BC and AD, though BCE and CE are acceptable, as long as usage is consistent throughout a publication.

  • INCORRECT: Her research concluded that the frozen man probably died somewhere around 7 BC and not 7 CE, as commonly held.
  • CORRECT: Her research concluded that the frozen man probably died somewhere around 7 BC and not AD 7, as commonly held.

2. Set the terms AD, BC, BCE and CE in capitals without periods. When using Christian Era dating, AD precedes the date and BC follows it.

  • INCORRECT: According to scholars, Jesus was probably born between BC 8 and BC 4, making him between 4 and 8 years old in the year he is commonly thought to be born.
  • CORRECT: According to scholars, Jesus was probably born between 8 BC and 4 BC, making him between 4 and 8 years old in the year he is commonly thought to be born.

century

1. Use ordinal numbers for centuries, spelling out numbers less than 10. Do not use superscript. Lowercase the term for a particular century.

  • INCORRECT: Leonardo da Vinci invented the helicopter—but not the corn popper—in the Fifteenth Century.
  • CORRECT: Leonardo da Vinci invented the helicopter—but not the corn popper—in the 15th century.

See also F.general usage.

2. When using proper names in running text, follow the practice of the company or organization whose name includes a particular century.

  • INCORRECT: The producer working on a film for 20th Century Fox was looking for a 21st-century fox to star in it.
  • CORRECT: The producer working on a film for Twentieth Century Fox was looking for a 21st-century fox to star in it.

dates

1. Use cardinal numbers, not ordinal numbers, with dates, except in the case of formal programs or invitations, or in a direct quote.

  • INCORRECT: May 7th, 1977
  • CORRECT: May 7, 1977

2. When referring to a month, day and year, separate month and year with a comma. Do not use a comma to separate month and year when no day is cited.

  • INCORRECT: The date of the fete is set. It’s May, 2007, specifically May 7, 2007.
  • CORRECT: The date of the fete is set. It’s May 2007, specifically May 7, 2007.

3. Use a comma between the day and year in a date. Use a comma following the year in a date. Do not use a comma when only the month and year are written.

  • CORRECT: Calvin College dedicated Calvin’s Crossing on May 8, 2002, with a ribbon-cutting ceremony.
  • CORRECT: Calvin College dedicated Calvin’s Crossing in May 2002 with a ribbon-cutting ceremony.

See also F.dates.

decades

1. Do not use an apostrophe before the s when indicating a full decade of a particular century.

  • INCORRECT: Many Calvin alumni remember campus life in the 1960’s with mixed feelings.
  • CORRECT: Many Calvin alumni remember campus life in the 1960s with mixed feelings.

2. When using an apostrophe to abbreviate a decade, the apostrophe indicates the years omitted. Use (’) not (‘).

  • INCORRECT: According to surveys, Calvin alumni from the ‘80s miss the “big hair” look.
  • CORRECT: According to surveys, Calvin alumni from the ’80s miss the “big hair” look.

See also C.graduation year/ exit year.

months

1. The months of January, February, August, September, October, November and December may be abbreviated as Jan., Feb., Aug., Sept., Oct., Nov. and Dec. Do not abbreviate the months March, April, May, June or July.

  • INCORRECT: The annual Meeter Center masked ball will be held 7-11 p.m., Mar. 6 in the Willow Room of the Prince Conference Center.
  • CORRECT: The annual Meeter Center masked ball will be held 7–11 p.m. March 6 in the Willow Room of the Prince Conference Center.

2. Do not abbreviate a month when it is not preceded by a day.

  • INCORRECT: Two things were banned at the annual Meeter Center masked ball, held in Oct.: controlled substances and people dressed as Servetus.
  • CORRECT: Two things were banned at the annual Meeter Center masked ball, held in October: controlled substances and people dressed as Servetus.

seasons

Do not capitalize the names of the seasons.

time of day

1. Use numerals for hours of the day. Lowercase a.m. and p.m. with periods in between.

  • INCORRECT: While the awards ceremony was slated to start at 7 PM, the athletes could not resist commencing the ceremonial “taunting of the mascot” at 5 pm.
  • CORRECT: While the awards ceremony was slated to start at 7 p.m., the athletes could not resist commencing the ceremonial “taunting of the mascot” at 5 p.m.
  • CORRECT: Stella’s first class is at 10:30 a.m., and she’ll be sleeping until then as is her wont.

2. Only use :00 when noting the time in an events timetable.

  • CORRECT: Retreat Schedule

8:00 a.m. breakfast
9:45 a.m. stroll
10:00 a.m. brunch
11:00 a.m. nap
11:45 a.m. strategizing
noon lunch

3. Do not spell out hours of the day or use the word o’clock, except in the case of formal programs and invitations.