Today’s reflection is in response to a question I received through the feedback survey for my newsletter, Indexing Matters. Thank you very much for your question, and my thanks to everyone who took the time to provide feedback. Your thoughtful responses are very encouraging and have given me good ideas for what to write and focus on.

(And if you haven’t yet given feedback or asked a question about something that is puzzling you about indexing, and you would like to do so, the link to the survey is here. It is anonymous and only contains four questions.)

The question is:

This is an excellent question. It is more common in certain disciplines to include more than one index. I think the key, when deciding whether or not to include more than one index, is to figure out the underlying why. For that, I think there are two main factors to consider, in addition to discipline expectations. What is the purpose of the index? And, what is the scope of the index?

What is the Purpose of the Index?

For most indexes, the focus is on discussions. The reader should be able to go to the specified page and learn something of value and substance. Passing mentions are left out. Citations are also typically ignored. The index acts as a filter to provide relevant information to the reader.

In some cases, though, the goal is to instead pick up all mentions, including passing mentions and citations. A scripture or ancient sources index is a great example, as that is intended for readers to find every instance a chapter and verse is cited. Name indexes also tend to be focused on mentions, including citations. In these cases, subheadings are typically not used and long strings of locators are acceptable. The goal is to allow readers to see at a glance how often, and when, someone or something is referenced.

In terms of whether to include one index or multiple, think about the purpose of the index. If the goal is to provide a comprehensive road map to the discussions contained within the book, then a single index covering everything is probably the right choice. If there is an element for which you want to pick up all mentions and to provide a quick overview, then that is probably a good element to split out into its own index. This way each index can have its own purpose and the separation can also be a signal to readers to expect something different from each.

A good example are the two indexes for Ancient Pathways, Ancestral Knowledge: Ethnobotany and Ecological Wisdom of Indigenous Peoples of Northwestern North America, by Nancy J. Turner (McGill-Queen’s University Press, 2014), which was indexed by François Trahan. François actually won the inaugural Ewart-Daveluy Award, from the Indexing Society of Canada/Société canadienne d’indexation, for these indexes. The first index is an “Index of Plant Species,” in which the plants are indexed by taxonomical names. There are no subheadings and readers can quickly see how often a plant is mentioned. The second index is a “General Index,” which is focused on discussions. In addition to concepts and other types of information, all of the plant species are double-posted in the General Index under their common names and, for those species extensively discussed, subheadings are used to guide readers in their search. These two indexes works well together because they gives readers a choice to search by either common or taxonomical name, and readers can decide if they want a quick overview of the number of references or if they want a more in-depth look at the discussions. If you are interested, the indexes can be viewed here.

What is the Scope of the Index?

Another consideration is to look at the scope of indexable material. A general index contains everything—all relevant names and subject matter. To sort and separate a general index by type of information is to potentially create a dozen or more indexes—for animals, plants, people, companies, concepts, court cases, trains, medical equipment, etc…—whatever makes sense for that book. Creating multiple indexes, each narrowly focused, is not practical and would probably confuse readers.

However, writing multiple indexes may make more sense if there are only two or three elements that you want to pick up. In this case, the two or three clearly defined indexes can be a way to signal to readers that this is it. Readers should not expect to find other types of information.

For example, in 2016 I indexed Exploring the Capital: An Architectural Guide to the Ottawa-Gatineau Region, by Andrew Waldron (Figure 1 Publishing). Two indexes were requested, one for buildings and one for designers, which covered people and architectural firms. Readers are offered two clear options for how to search. Another example is Hunters on the Track: Willian Penny and the Search for Franklin, by W. Gillies Ross (McGill-Queen’s University Press), which I indexed in 2019. In that case, the client did not have the budget for a full index but still wanted something. The press suggested two indexes, one for names and one for places. I suggested adding a third, for ships, as ships also seemed important to the narrative and Arctic exploration. So that is what we did: three indexes, no subheadings, focused on a quick overview of all people, places, and ships. Nothing else was indexed.

All that said, even if only two or three elements are picked up, a single index may still be the best choice. As I recently discussed, my index for To See What He Saw: J.E.H. MacDonald and the O’Hara Years, 1924-1932, by Stanley Munn and Patricia Cucman (Figure 1 Publishing, 2024), at the publisher’s request, only focused on paintings, people, and places. All three elements are contained within a single index. I think it still works, though, because there is not much else that is indexable. Readers are unlikely to be looking for anything else, and so the index isn’t contravening reader expectations by pretending to be more general than it actually is.

Discipline Conventions

As I mentioned at the beginning, it is common in certain disciplines to include multiple indexes, whether that is a scripture index in Biblical studies texts or a separate name index so readers can see who is cited. If you are aware of these conventions and expectations, then that can also be a good reason to follow suite. However, I suggest also asking yourself if there is a further underlying reason why multiple indexes makes sense. Do different elements in the book need to be handled differently in the index? Is everything being indexed or is the focus much narrower?

The goal, as always, is to make the index(es) user-friendly and to meet user expectations. It may be that following convention is the best way to meet those expectations, or it may be that the convention doesn’t really make sense for your purpose, in which case I would go ahead and write the index(es) that would be the most useful.

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For the books I typically index, both trade and scholarly books in the humanities and social sciences, a single, general index focused on discussions is usually what is required and expected. With the exception of scripture indexes, I usually prefer to write a single index which includes everything. That said, multiple indexes are definitely an option. They can be another tool that you can use to both meet expectations and shape expectations, depending on what you want the indexes to accomplish.