19.6 Number references
In references to pagination and dates, use the smallest number of figures consistent with clarity: see
Be as specific as possible in your references. For this reason, do not use section or clause numbers instead of page numbers unless they are frequent and the entire index is to be organized that way. Avoid using ‘f.’ and ‘ff.’; give instead the first and last pages of the material: 123–5, for example, denotes one continuous discussion spanning three pages, whereas 123, 124, 125 denotes three separate short references. Avoid using passim (‘throughout’). Cite the page extent of a chapter and not, for example,
References to footnotes and endnotes may simply give the page number. If more detail is desired, give references to footnotes and endnotes in the form ‘word 90 n. 17’ for one note and ‘word 90 nn. 17, 19’ for two or more; each has a full point and a space after the abbreviation. There is no need to give the note number where there is only one note on the page cited; in such cases it is Oxford style to insert a thin space between page number and ‘n.’
To provide the most effective help to the reader, a general index serving more than one volume must include the volume number as part of each locator, regardless of whether the pagination runs through volumes in a single sequence or begins anew with each volume. Volume numbers may be styled in Roman numerals, often in small capitals, separated by a full point: ‘word iii. 90’. Indexes to a group of periodicals may have both the series and volume number as part of the locator.
Though simple page references are often sufficient, it may be appropriate to mark figures denoting references to illustrations in italic or bold, or with some typographic symbol (such as an asterisk or dagger), and provide an introductory note at the start of the index in the form Italic/bold numbers denote reference to illustrations. Some authors use a similar treatment to flag passages that are particularly significant or include definitions; again, explain this practice at the start of the index (but bear in mind that readers often ignore these explanatory notes).