DATES, NUMBERS, AND PERCENTAGES
CMS16, 6.45 and elsewhere, gives date examples in both month–day–year (e.g., May 31, 2013) and day–month–year (31 May 2013) formats. CMS15, 6.46, recommended the former, as being the most commonly used in the United States. CMS16, 9.36, notes, however, “In documentation and in tables, if numerous dates occur, months may be abbreviated, and the day–month–year form, requiring no punctuation, may be neater. . . .” To avoid situational date formats, and for the sake of consistency, Notes prefers day–month–year in all cases. This also is the format used throughout Garner3, and by the U.S. military.
- 1560s not 1560's
- Paris in the 1830s and 1840s not 1830s and '40s (CMS16, 9.34)
Use en dashes (not hyphens) to connect dates and other numbers
- 1898–1903 not "from 1898–1903"; the following are also acceptable: from 1898 to 1903, or between 1898 and 1903 (CMS16, 9.59)
- Use 2000–2001 not 2000–1 or 2000–01; 2000–2004 not 2000–4 or 2000–04 (see CMS16, 9.60)
- Use 2001–2 not 2001–02 or 2001–2002; 2001–4 not 2001–04 or 2001–2004 (see CMS16, 9.60)
- Use the traditional number-range format described in CMS16, 9.60, for ranges of dates, except for birth–death dates, which use all the digits.
- Wolfgang Amadeus Mozart (1756–1791), not 1756–91.
- For uncertain birth or death years, use "?" before the year in question.
- John Benet (d. ?1458); Antoine Brummel (ca. 1460–?1512/13); Alexander Agricola (?1445/46–?1506)
- This differs from CMS16, 6.66, which places the "?" after the year in question.
- For an open date, use (1999–) (no space after the en dash) not (1999– ) (see CMS16, 6.79)
A forward slash is sometimes used in dates (instead of an en dash) to indicate the end of one year, and the beginning of the next (e.g., 2014/15, no space). This is commonly seen in designating a school year, a performance season, or for journal issue or volume numbering. Prefer whichever format is used by the item being quoted.
- Use all the digits for groups of works, etc.
- Bach's cantatas BWV 812–817, not Bach's cantatas BWV 812–17.
- Numbers beginning a full sentence are always written out.
- "Two hundred and sixteen [not 216] motets appear in the opening fascicles of the manuscript." But: "There are 216 motets in the opening fascicles of the manuscript."
- Arabic numerals: Use act 1, scene 2, movement 3, etc., not act I (or Act I), scene II, movement III (CMS16, 9.27).
- Roman numerals: Use violin I, violin II, etc., not violin 1, 2. Similarly, use choir I, choir II; cantus I, cantus II; Kyrie I, Kyrie II.
- "In most numerals of one thousand or more, commas are used between groups of three digits, counting from the right" (CMS16, 9.55). Thus, "Out of 1,425 [not "1425"] books from the 'Books Recently Published' columns in 2012, 1,315 [not "1315"] (92 percent) have been used in calculating this year's price trends."
- Commas are not used in page numbers, line numbers (in poems and plays), music publishers' plate numbers, street addresses, and years.
- "The letters in ordinal numbers should not appear as superscripts (e.g., 122nd, not 122nd)" (CMS16 9.6). Beware that Microsoft Word defaults to superscript in these instances; use the Fonts menu to highlight and correct these.
- Use numeral, plus "percent," not the percent sign % (see CMS16, 9.18).
- 50 percent not 50%; 30 to 50 percent not 30 to 50% (also not thirty to fifty percent)