Editing Indexes

Fred Brown
Allegro Technical Indexing


(Originally published in The Technical Editor, March 1999, Institute of Technical Editors. Updated June, 2007.)

Like any well-written document, an index needs to be edited. Editing ensures consistency, clarity, completeness and accuracy. And an effective index contributes substantially to the usability of a document.

Indexes assist users to find specific information within a document, in print or online. As such, index headings refer to concepts, tasks or objects—not simply to individual words in the text.

Three types of relationships serve to link index headings together:

  • equivalence—synonyms, e.g., audience and readers 
  • hierarchy—broader or narrower terms, e.g., paintings and watercolours 
  • association—overlapping meaning, e.g., gold and money 
These relationships are expressed through cross-references and double-posting. Thus an index forms a complex web, or "searchable structure," that assists the user to find information.

Editing an index can take almost as much time as writing the first draft—and possibly longer if the index markers embedded in the main document are difficult to access. Editing requires close attention to both detail and the overall structure of the index.

Although time consuming, be sure to correct the index markers in the main document rather than editing the text of a generated index directly. Otherwise, when you regenerate the index, all your editing will disappear. Professional indexers often use specialized stand-a-lone indexing software to help them write and edit an index quickly; once complete, the index headings can be sorted by page number and the index markers entered into the main document.

This article provides a checklist of items to assist you:

  • main headings 
  • synonyms 
  • number of undifferentiated page references 
  • number of subheadings following a main heading 
  • parallel structure in subheadings 
  • double-posted headings 
  • cross-references 
  • alphabetization of subheadings 
  • capitalization, pluralization and spelling 
  • personal and geographic names 
  • page references are accurate 
  • mechanics for an online index 
Note: The examples in this article are based, as much as possible, on real indexes. As such, you will see different styles for formatting index headings, including cross-references and capitalization.

Checklist Items 

Main Headings 

Evaluate main headings individually bearing in mind that they form the primary access points to the index. Does the heading reflect the material in the main document? Is the heading clear and concise? Does the wording reflect what the user would look up?

Index headings should reflect a consistent level of depth across the document.

Archaeology, 128–145 

  Ayuthaya period, 246–250, 266 
  ancient Thai religions, 245 
  Buddhist, 251–255, 264 
  Central Plains, 250 
  cho-fa, 265 
  classical Thai, 248, 252–260 
  Khmer, 263 
  modernizing influences, 253, 267 
  Sukhothai, 249 
In the above example, the heading for "Archaeology" needs to be expanded to match the level of depth in the "Architecture" heading. Subheadings will enable users to quickly find specific information about archaeology.
  Ayuthaya ruins and restoration, 128–130 
  Ban Chiang, diggings at, 144 
  Museum, Silapakorn University, 132 
  Neolithic remains, 136–144 
  Northern kingdoms, 129, 143, 145 
  Phayao, 131–135 


Synonyms allow users to use their own words when searching for information. You might ask your client to review the main headings in the index and suggest any synonyms. Look at competitors’ manuals for their terminology, especially if you seek to attract customers from other camps. Consider terms used in other environments, e.g., Mac, PC or Unix. User analysis, such as contextual inquiry, may reveal user terminology as well.

You may enter a synonym

  • as a "See" cross-reference 
    First World War, 120, 208–33

    Great War 1914–18. See First World War 
  • or by double-posting 
    Crohn’s disease, 112–113
    Ileitis, 112–113
Where you want to instruct the user about the standard terminology used in the document, consider using a "See" cross-reference from a synonym not used in the text to the term that is used. If space for the index is a concern, consider using the "See" reference when there are more that three subheadings after the main heading. Some online publishing systems (e.g., Windows Help) do not allow "See" cross-references; so you will need to use double-posting for synonyms.

Number of Undifferentiated Page References 

In a technical publication, there should ideally be only one or two page references in a main heading or subheading. Undifferentiated page references simply cause additional work for users, who may already feel frustrated. More than three or four undifferentiated page references usually indicates a problem.

If a main heading has too many undifferentiated page references, simply create a number of subheadings.


Platemaking, 78, 79–80, 84, 86, 90 See also Process camera 
Platemaking, See also Process camera 
  gravure, 84 
  letterpress, 79–80 
  offset lithography, 86 
  other processes, 90 
  overview, 78 
In a two level index, if there are too many undifferentiated page references in a subheading, you cannot simply divide the subheading into sub-subheadings. One solution is to raise the subheading to a main heading with its own subheadings and make a "See also" cross-reference from the original main heading.


  adding with external links 142 
  media elements 26, 27, 114–16, 281, 340–345 
  mixing media 340 
media elements 340–345 
  creating 26 
  indexing nonverbal elements 281 
  specifying 26, 27, 114–116

  See also media elements 
  adding with external links 142 
  mixing media 340 

Number of Subheadings Following a Main Heading 

As a rule of thumb, more than 15 or so subheadings following a main heading may indicate a structural problem. The following example comes from a manual about using fax software on a PC.
  annotating 1–1, 1–5, 1–6 
  archiving 1–6 
  assembling 1–4 
  attachment 1–4, 3–19, 8–2, 13–5 
  attachment folders 1–7 
  billing code 1–6 
  clean up 1–1, 1–6 
In this example, the main heading is too broad, given that the manual is about faxing. To fix the problem, simply eliminate the main heading and raise the subheadings to main headings.

Parallel Structure in Subheadings 

To the extent possible, try to follow a consistent grammatical structure in subheadings.
image list 

Double-Posted Headings 

Verify that the subheadings and page references match in any double-posted headings. In the following example, the main headings are synonyms; so the subheadings and page references must be exactly the same in both the headings.
directories 21–25 
  in Explorer 107 
  finding 72 
  shortcuts 84 

folders 21–25 
  in Explorer 107 
  finding 72 
  shortcuts 84 
In this next example, "saffron" appears as a subheading under "Rice," and "rice" appears as a subheading under "Saffron."
  basmati 106 
  boiled 143 
  with peppers 66 
  quantities 130 
  saffron 105 
  salad, nutty spicy 144 

Saffron 181 
  rice 105 
  sauce 136 
If subheadings are missing from an heading, a user may look at the heading and conclude that a topic is not covered in the document, when in fact it is.

Subheadings that users may wish to look up directly should also be posted as main headings. In the following example,  "balusters" is listed as a subheading under "porches" and is also posted as a main heading.

balusters, 107 

  balusters, 107 
  enclosing, 106 
  preserving wood porches, 105 


Check that each cross-reference ("See" and "See also") refers to an heading and that they match exactly. Also check for circular cross-references. In the example below, the "See also" reference under "annotations" is circular and should be removed.
annotations 203 
  See also commentary 
  annotating authoritative works  179 
  letting users talk back  201 
  linking to comments  129, 136, 165, 179 
  for pictures  301 

commentary. See annotations 
Also ensure that cross-references go directly to an heading, not to another cross-reference. In the example below, the "See also" reference under "weight control" should be changed to go directly to "fitness."
exercise. Seefitness 

fitness, 21–25, 81, 124 

weight control, 16, 45–48 
  See also exercise 

Alphabetization of Subheadings 

Leading articles and prepositions in subheadings should not be alphabetized. In FrameMaker you can define how to alphabetize a specific subheading; however, in Microsoft Word you will need to fix the index manually after it’s generated. In the following example, "into or out of an" in "into or out of an eddy" and "on" in "on University River" are ignored when alphabetizing the list of subheadings.
Back ferry (setting) 
  advantages, 87 
  double, 85–87, 99, 101–102 
  into or out of an eddy, 87 
  efficiency, 21 
  problems, 92 
  running a tight bend, 111 
  solo, 90 
  on University River, 86 
  varying your speed, 85 
In general, only use articles or prepositions when necessary to clarify meaning.

Capitalization, Pluralization and Spelling 

Establish a style for capitalization. Older style indexes often capitalize the first letter of each main heading. In technical documentation, it’s wise to follow the capitalization used in the text because capitalization can affect the meaning of specific terms or may be incorrect if changed.
OPTIND variable 
Orange Book security 
PostScript language 
SHELL variable 
shell variables 
Generally, nouns where we can ask "how many?" are expressed in the plural form.
Nouns where we can ask "how much?" are usually expressed in the singular form.
Decide on how you will handle pluralization and be consistent throughout the index.

Be careful about American, Canadian and British spellings. Employ the spelling used in the main document.

Personal and Geographic Names 

Many rules apply to personal names. Generally, you enter the surname followed by forename or initials.
Freud, Sigmund 
Special rules apply to handling prefixes in French, German and other European names. Different rules may apply to names of Asian origin as well.
Am Thym, August 
Aubigné, Théodore Agrippa d’ 
Beethoven, Ludwig van 
Cheng Shifa 
Du Guesclin, Bertrand 
Las Heras, Manuel Antonio 
Mya Sein 
Names of geographic features that begin with the type of feature, such as Mt. or Lake, are inverted when entered in the index.
Ontario, Lake 
Revelstoke, Mt. 
Scott, Cape 
On the other hand, you do not invert proper place names that begin with a type of feature.
Cape Scott Provincial Park 
Lake Louise 
Mt. Revelstoke National Park 
For specific guidance on handling personal and geographic names, see Mulvany pages 152–182 or The Chicago Manual of Style (14th edition) pages 731–737. For the correct spelling or form of a personal name, you may wish to check a standard reference source such as Merriam-Webster’s Biographical Dictionary or the Encyclopedia Britannica.

Page References are Accurate 

Check a small number of page references (e.g., 5%) to ensure that nothing has gone wrong. When an index is embedded in a document, sometimes one can forget to regenerate the index after making final changes to the text.

Mechanics for an Online Index 

In online indexes, check that hypertext links and any automated search capabilities work properly.

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