Non-alphabetical ordering

Main headings are invariably arranged in a purely alphabetical ordering, assuming that the rules for alphabetizing them specify how headings beginning with a function word, symbol or numeral should be treated. If that is so, and it should be, we can say that non-alphabetical ordering is used only with subheadings and not with main headings.

The fact that it may be used with subheadings does not mean it must be used with them. It is appropriate to use it only when using it makes the index easier to use than it would have been if the affected subheadings had been arranged alphabetically.

When it is used, it does not have to be applied to the subheadings of all main headings. In fact, it is generally true that, when it is used, the subheadings of most main headings are arranged using the same alphabetical alphabetization system used for main headings.

However, whereas all main headings are arranged using the same alphabetization system (either letter-by-letter or word-by-word alphabetization), different groups of subheadings may be arranged using different non-alphabetical ordering schemes.

The primary non-alphabetical ordering schemes are these:

• Chronological ordering, in which subheadings denoting events are arranged in chronological order. All references to the event are posted with the subheading denoting it. For example:

  House, Porter T.     birth, ...     father's death, ...     military service, ...     marriage, ...     arrests, ...     imprisonment, ...     divorce, ...     death, ...

  This ordering is particularly useful when the story being told has a strong chronological element, as is the case in many historical or biographical works, but the events themselves are not related in the order in which they occurred, which is also the case in many historical or biographical works. Works about other fields are not likely to warrant much chronological ordering.
• Evolutionary ordering, in which subheadings denoting successive phases or periods are arranged in phase order. This scheme is particularly useful in indexes to works about sciences in which evolution is important, such as biology and geology, and in works about the development or deployment of products or systems. For example:

  fossils     Silurian, ...     Devonian, ...     Carboniferous, ...     Permian, ...     Triassic, ...     Jurassic, ...     Cretaceous, ...

  product X     needs analysis, ...     requirements, ...     design, ...     development, ...     deployment, ...     maintenance, ...     retirement, ...

  product Y     needs analysis, ...     requirements, ...     design, ...     development, ...     deployment, ...     maintenance, ...     retirement, ...

  The primary difference between phases and events is that the number, names and order of phases applicable to an object type are defined in advance and are expected to apply to all instances of the type, whereas events are often contingent and therefore cannot be expected to apply to all instances of a type. Hence, main headings with the same subheadings are not uncommon with evolutionary ordering but they are almost unheard of with chronological ordering. The following examples should help clarify the difference:

  House, Porter T.     birth, ...     father's death, ...     military service, ...     marriage, ...     arrests, ...     imprisonment, ...     divorce, ...     death, ...

  Johnson, Harry     infancy, ...     childhood, ...     adolescence, ...     adulthood, ...     senescence, ...

  Smith, Albert     infancy, ...     childhood, ...     adolescence, ...     adulthood, ...     senescence, ...

  As they indicate, there are often many more potentially indexable events than phases. The reason is that phases are typically understood to occupy some period of time, whereas events are often understood to be indivisible or instantaneous.
• Page number ordering, in which subheadings are arranged in accordance with the lowest page number associated with them. The subheading with the lowest-numbered page locator is placed first, regardless of where it would be placed if placed alphabetically; the one with the next lowest-numbered page locator is placed second, regardless of where it would be placed if placed alphabetically; and so on. For example:

  testing     rationale for, 22, 175     integration tests, 147-151, 190     system tests, 163-170, 191     acceptance tests, 173-177     metrics for, 180-181     unit tests, 187     environments for, 217

  Years ago, page number ordering was common because, without computers, alphabetizing headings was tedious and error-prone. Alphabetizing main headings had to be done, but alphabetizing subheadings could be avoided by using page number ordering, which meant that new subheadings could be added without having to re-order ones identified earlier. Today, the few presses that require it do so generally only for biographies or books about history and based on the belief that it results in chronological ordering. Their assumption is that the story in such books is generally told in chronological order, so page number ordering will therefore also result in chronological ordering. However, page number ordering and chronological ordering do not necessarily produce the same results because events may occur in one order but be described in another. As the number of out-of-order events in the story increases, so too does the number of subheadings in page number order that will be out of chronological order. The greater that number, the greater the likelihood that there will be no apparent order. There is another potential problem as well: page number ordering may cause aspects of a topic that are related to be separated because it reduces the importance of making the most significant term in a heading the heading's initial term. Although these potential problems may limit its usefulness, page number ordering is nevertheless the only non-alphabetical ordering scheme that may be required to be used throughout an index. Generally, the requirement is applied only to books in which the story is in largely chronological order, such as biographies and some historical works. Page number ordering can be applied throughout an index because its criterion - possession of a lowest page number - typically applies to every subheading. The only exceptions are subheadings that are used for grouped ordering, which is described below.
• Chronological-numeric ordering, in which subheadings denoting sequentially numbered instances of a type are ordered sequentially. For example:

  International Conference on Software Engineering     ICSE-9 (Monterey, California, 1987), ...     ICSE-17 (Seattle, 1995), ...     ICSE-18 (Berlin, 1996), ...     ICSE 1997 (Boston), ...     ICSE 1998 (Kyoto), ...

  This ordering applies only in cases where there are no unnumbered instances of the events, documents, etc., interleaved among the numbered ones. When unnumbered ones are interleaved, the ordering is chronological rather than chronological-numeric. Dates are used as qualifiers to make the point in the following example:

  French revolutionary and Napoleonic wars     First Coalition (1792-1795), ...     Italian campaign (1795-1797), ...     Egyptian campaign (1798-1801), ...     Second Coalition (1798-1802), ...     Third Coalition (1804-1805), ...     Fourth Coalition (1806-1807), ...     Peninsular War (1808-1814), ...     Fifth Coalition (1809), ...     invasion of Russia (1812), ...     Sixth Coalition (1813-1814), ...     Hundred Days (1815), ...

  The dates also indicate an inherent problem with chronological ordering: it may entail serializing parallel events. The more parallel events there are, the less obvious the chronology, even when dates are added.
• Classified ordering, in which subheadings are ordered in accordance with a hierarchic classification scheme. For example:

  Animalia   Chordata     Vertebrata       Neognathae         Passeriformes           Fringillidae             Serinus               Serinus canaria                 "Tweety Bird", ...

  Cosa Nostra   The Commission     Capo di Tutti Capi (dons)       Bougatas (underbosses)         Consiglieres (counselors)           Caporegimes (lieutenants)             Soldiers/Button Men               "Fist", ...               "Tommy Whacker", ...

  The examples are unrepresentative classified orderings because the hierarchies are exceptionally deep, all headings are capitalized and all locators are at the lowest level. Deep hierarchies are likely to cause usability problems, especially when members of the audience are unfamiliar with the criterion used to structure the hierarchy. Unfamiliarity with the criterion is particularly likely when the structure is one the indexer created specifically for the index. Many indexers seem to be unaware that there must be only one criterion and that it should be readily apparent to users. The fact that an alternative structure may be better known by users and the fact that the changes in the world may have made the ordering's structure obsolete are other reasons users may find classified orderings to be unordered or unclear.
• Grouped ordering, in which a very large number of subheadings to a main heading are organized into named groups that are almost never listed alphabetically, although they may be. Grouped ordering is suitable only when a main heading has enough subheadings to require several columns or pages in the index, such as in indexes to biographies and historical works, which often have main headings with hundreds or thousands of subheadings. The large number of subheadings in those works reflects the fact that the story being told is full of events. It can become extremely difficult to find anything in a list that long, especially if the list is arranged non-alphabetically and presented in run-in style. Hence, an extra level of headings is added to reduce the number of headings that need to be examined to find something. The group titles that are introduced are typically distinguished typographically from other headings. In the example that follows, the events in a person's life have been grouped under titles representing phase's in the human life cycle and subheadings have been arranged alphabetically to highlight the group titles.

  House, Porter T.      infancy         birth, ...         weaning, ...      childhood         father's death, ...         friendships, ...      adolescence         early sexual experiences, ...         membership in Street Lords, ...         relationship with "uncles", ...         truancy, ...      adulthood         alcoholism, ...         arrests, ...         divorce, ...         engagements, ...         imprisonment, ...         infidelities, ...         marriage, ...         military service, ...         unemployment, ...      senescence         confinement to nursing home ...         death, ...

  The common life cycle phases used to order events in the example are not likely to be used in a real index because there are too few of them. Using them there is likely to result in very large groups, which would defeat the purpose of group ordering. Hence, group titles tend to be unique to the main heading, such as life at Coxcomb Manor, travels in India, lepidopterological pursuits, headmastership of Glumley Hall. As a result, there may be no obvious criterion for ordering them, either to the indexer or the user.

Guidelines for using non-alphabetical ordering schemes:

• House style trumps all other guidelines, including those that follow. If you have doubts about what to do, ask your editor.
• Use non-alphabetical ordering only if it is clearly more beneficial to users than alphabetical ordering. In rare cases, indexers are required to use page number ordering for all subheadings in an index. Generally though, the decision to use non-alphabetical ordering is one the indexer makes on a case-by-case basis. When deciding which order to use, you should remember that, when they are asked to arrange terms in order, most people are comfortable only with arranging terms in simple numeric or alphabetic order. Some even have difficulty arranging them alphabetically beyond the first few letters of the alphabet.
• Place all page references related to a given subheading following it and in page number order. Although a given subheading may appear beneath many main headings, the no two subheadings of a given main heading should be the same. There should be no duplicates in the set, not even when page number ordering is used.
• If possible, limit the number of subheadings to about a dozen. If a large number of subheadings are arranged in a non-alphabetical order, users may become annoyed by the apparent lack of order or by the need to read through lots of subheadings to find what they are looking for. That may happen even when chronological ordering is used because serialized parallel events become more likely as the number of events denoted by subheadings increases.
• Avoid using a classified ordering scheme. Users may not know the criterion, classifications change over time and become outdated, and it is not easy to incorporate nonhierarchical aspects of the subject into the structure.
• Do not use a non-alphabetical ordering scheme if it is not readily apparent how its ordering criterion applies to all the affected subheadings. This is a reminder that alphabetization always involves a criterion for arranging headings and that the criterion always is applied to all headings to be arranged using the scheme. It is also a generalization of the point made in the preceding guideline that it is difficult to incorporate nonhierarchical aspects of a subject into a classified (hierarchical) ordering. Similarly, it is difficult to incorporate unnumbered subheadings into a chronological-numerical ordering, subheadings about topics unrelated to a specific phase into an evolutionary ordering, and subheadings about things other than events into a chronological orderings of events. The lesson is that, as the number of subheadings the non-alphabetical criterion does not obviously apply to increases, so too does the likelihood that alphabetical ordering will serve users better than non-alphabetical ordering.

To top of page