6.4.3 Roman Numerals

In some situations, Roman numerals can be or commonly are used instead of Arabic numerals:

• When numbering and referring to the preliminary pages of books, theses or journals, lowercase Roman numerals are conventional (p.viii).
• Roman numerals can also be used for the volume, part, chapter, section and/or appendix numbers of books, theses or journals, for the section numbers of long poems, for the act and scene numbers of plays and for the numbers of legal documents. Depending on the circumstances, uppercase or lowercase letters may be used, but one format should be used for the same purpose throughout a thesis (‘Appendix V’ and ‘Appendix VII,’ not ‘Appendix V’ and ‘Appendix vii’). In some styles the capitalisation of the numerals might depend on the capitalisation of the words that precede them: ‘Chapter V’ but ‘chapter v.’ Using capitals for one level in a hierarchy and lowercase letters for another can add clarity in references and cross references: for example, ‘V.iv’ might be a reference to the fourth part of Appendix V in a thesis or the fourth scene of Act V in a play, depending on the topic under discussion.
• Uppercase Roman numerals are often used to number movie sequels (Shrek II), and they are the normal format for numbers in the names of boats (Pachena II), whereas spacecraft, for instance, tend to use Arabic numerals.
• Uppercase Roman numerals are also the norm in the name of an individual named after a grandparent (‘Edward Buckingham II’; were he named after his father, ‘Jr’ or ‘Jr.’ would follow the name instead), and in the names of monarchs, emperors, popes and prelates (for example, ‘King Henry V’ and ‘Pope John Paul II,’ though these can also be written out in running text: ‘Henry the Fifth’).
• A Roman numeral (usually lowercase) can be used to indicate the month in dates, and in foreign languages Roman numerals are often used to indicate centuries (see the discussion of dates and centuries in Section 6.4.4 below).
• Roman numerals are often used when transcribing material from early texts such as classical works and medieval manuscripts. In such texts, a ‘j’ is sometimes used at the end of a string of ‘i’s in a Roman numeral (xiij): this is usually retained in a literal transcription, but changed to an ‘i’ in a modernised rendition.
• Roman numerals are sometimes used to number the items in lists, but they can become cumbersome in such situations, so Arabic numerals are best when there are many items in a list (see Section 5.5.2).
• Roman numerals are occasionally used for numerical references or footnote or endnote numbers, but here, too, they can quickly become cumbersome, so Arabic numerals are preferable (see Section 7.2.2).

If you need to use Roman numerals in your thesis and are unsure of how they are formed and used, see the opening comments in Section 11.4 of Ritter (2005) as well as Section 9.69 and the list of Roman and Arabic numerals (p.398) in the Chicago Manual of Style (2003). Keep in mind that although Roman numerals can be effective in a variety of situations, they tend to be both awkward and unclear when they are elided, so elision is best avoided when using them (for more information on eliding numbers, see Section 6.4.7 below).

6.4.4 Dates, Decades, Centuries and Eras

There are various ways in which to express dates of different kinds in the English language. For full dates, Arabic numerals should be used for the day of the month and the year, while the month is usually written out as a word. In British English the common format is ‘5 November 2014’ and in American English, ‘November 5, 2014’; in both, no comma appears between the month and year if no day is given: ‘November 2014.’ Abbreviations can be used for the names of months – ‘Feb.,’ ‘Oct.’ and ‘Nov.’ – but the full name should always be written out when the month is used alone (‘February,’ ‘October’ and ‘November’). Ordinal numbers are generally only used when the day appears alone – ‘they’re coming on the 10th’ – although ‘the 10th of November’ does replace ‘10 November’ in some instances; generally speaking, one form or the other should be used consistently throughout a thesis. If the name of the day appears before the full date, it is followed by a comma: ‘Monday, 10 November 2014’ for British English and ‘Monday, November 10, 2014’ for American English. All-numeral dates are best avoided because of the potential for confusion – ‘10/11/14’ is 10 November 2014 in British English and October 11, 2014 in American English – so if you wish to use such dates in your thesis, the format should be explained and used with the utmost consistency; in British English the slashes can be replaced with full stops (10.11.14). Sometimes a Roman numeral is used for the month in this format, which eliminates potential confusion: ‘10.xi.14.’ The International Organization for Standardization uses the order year-month-day for all-numeral dates, with hyphens or en rules separating the elements (‘2014-11-10’); this format is often seen in technical contexts. For precise dates in astronomy, days (d), hours (h), minutes (m) and seconds (s) can be used (2013 April 5d 7h 14m 7.6s), as can fractions of days (2013 April 4.315). An exception to conventional date formats is presented by ‘9/11’ which is now internationally known as a reference to the attack on the World Trade Center Towers in New York on 11 September 2001, but it is good practice to use the full date at least on first mention.

Decades should be written as ‘the 1970s’ or ‘the seventies’ rather than ‘the 1970’s’ or ‘the ’70s,’ and the ages of individuals indicated in decades can be handled similarly – ‘he is in his seventies’ or ‘he is in his 70s.’ Sometimes using a word instead of a numeral for a decade implies more than simply a span of time: it can convey a greater sense of the cultural, political, social, intellectual and artistic characteristics of the decade (as in ‘the twenties,’ sometimes capitalised as ‘the Twenties,’ instead of ‘the 1920s’). Vague references such as ‘lately,’ ‘in recent years’ or even ‘in the last ten years’ that can become unclear or misleading as time passes should be avoided and more precise descriptions used instead (‘in the 2010s,’ for instance, or ‘from 1975 to 1984’). In formal running prose, centuries are usually written out as words (‘the thirteenth century’ or ‘the fifth century BC’), but in notes, tables, references and the like, abbreviations can be used: ‘the 13th cent.,’ for example. Uppercase (and sometimes lowercase) Roman numerals are often used in other languages to indicate centuries, as in ‘le XVI^e siècle’ for ‘the sixteenth century,’ but it is best to translate these into appropriate English forms. When dating medieval manuscripts, ‘s.’ for ‘saeculum’ (Latin for ‘an age’: see Section 6.3.11) along with a Roman numeral (generally lowercase) is often used, as in ‘s. xiii’ for ‘thirteenth century.’ The words expressing centuries require hyphenation when used as adjectives (‘a twenty-first-century problem’ or ‘a fourteenth-century manuscript’); sometimes a hyphen is added after ‘early,’ ‘mid’ or ‘late’ as well in both the noun and adjective forms – ‘the mid-thirteenth century’ and ‘an early-thirteenth-century manuscript’ – but these are technically better without the additional hyphen: ‘the mid thirteenth century’ and ‘an early thirteenth-century manuscript.’

AD (for Anno Domini or ‘In the Year of the Lord’) and BC (for ‘Before Christ’) are the most commonly used era abbreviations in English writing. To indicate BC dates, the abbreviation should follow the numerals – ‘465 BC’ or ‘14,000 BC’ – and notice that whereas four-digit numerals for specific years do not use commas, BC dates of five or more digits do, as do BP (Before Present) dates of five or more digits. AD, on the other hand, should appear before the numerals in a date – ‘AD 1367’ or ‘AD 1997’ – except when the date is written out (the thirteenth century AD). Neither BC nor AD, but especially the latter, is strictly required with dates unless there could be confusion between them or with other dating systems, but they should certainly be used to avoid potential ambiguity or to indicate a span of time that extends across both BC and AD dates: ‘93 BC to AD 123.’ To avoid Christian implications in dates, BCE (Before Common Era) and CE (Common Era) are often used; both abbreviations should follow the numerical dates – ‘189 BCE’ and ‘1256 CE’ – and so should the BP abbreviation for Before Present dates (with ‘the present’ fixed at AD 1950), which tend to be used by palaeontologists and geologists for times more than 10,000 years ago, although they can be used, like BCE and CE dates, more generally to avoid Christian references. For information on the use of other abbreviations for eras, such as AH (for Anno Hegirae, used for Islamic dates), AM (for Anno Mundi, for Jewish dating), AS (for Anno Seleuci, used in the Far East) and others, see Ritter (2005, Section 11.6.3). For radiocarbon dates that have not been recalibrated, a lowercase ‘bp,’ ‘bc’ or ‘ad’ is used. To learn more about the different calendars in English (Old Style vs. New Style, ‘modern style’ vs. ‘Lady Day style,’ regnal years etc.) and other traditions (Chinese, Greek, French, Japanese, Jewish and Islamic/Muslim), see, for instance, Cheney (2000), Sections 11.7 and 11.8 in Ritter (2005) and Appendix 11 in Butcher et al. (2006); for a wider exploration of calendar customs, see Blackburn and Holford-Strevens (1999).