3. Dates
3.1 For the Gregorian calendar we prefer BCE/CE abbreviations.
3.2 Centuries should be spelled out fully in main prose.
sixteenth century, eighth-century manuscript, early fifth-century vase
3.3 Date ranges always should be provided in full.
1000–1005, 1005–1015, 1950–19.76
3.4 For calendar dates we use the US format.
January 1, 2023
3.5 Decades are formed by adding a plural -s
1950s, 870s
3.6 Abbreviated years may be used if they are clear from context.
1950s, ‘60s, and ‘70s
3.7 For approximate years, use c. (circa).
Palladio's Palazzo Chierecati (c. 1550)