Subheadings are, I would argue, essential for a good index. Not everyone would agree, apparently, as evidenced by the indexes one finds with long strings of locators with perhaps the odd subheading tacked on at the end. But as a way to deliver additional information to the reader, and to break up and add meaning to those long strings of locators, subheadings are the primary tool available. Yet subheadings can also be poorly written or included, which can sabotage the whole purpose of using them in the first place. While I realize that different indexers vary on how they use subheadings, here are some of the common considerations I face about subheadings, and how I resolve them.
How many locators must an entry have before subheadings are needed?
My rule of thumb is about six locators before I add subheadings, but I also consider the context before making my final decision. For trade books I might allow up to seven or eight undifferentiated locators, under the assumption that trade books can often have lighter, less detailed indexes. I also consider how important the information behind the locators seem to be, as well as how important the entry is in the context of the index. It also depends on what type of information is being conveyed. A distinction between almond milk, soy milk, and goat milk, as subheadings under milk, for example, seems important to make even if there are only four locators. Alternatively, there could be nine locators on the same topic with very little to distinguish them, which would make subheadings seem forced. Ideally, my upper limit for undifferentiated locators is ten.
Going back to those nine similar locators—what if there are fifteen and breaking them down isn’t practical or possible?
I once faced this problem in a book of local history in which a few people, still alive, had been quoted extensively, with like fifteen or twenty locators each. On the one hand, I felt that it was important to index these people, as they were alive and members of the community. On the other hand, they were rarely the focus of the text, instead offering little comments here and there. For that reason, and also for space, subheadings did not seem appropriate, as it would have resulted in long lists of one subheading per locator. My solution was to use a fake subheading, appended to the main heading, along the lines of,
Smith, John, reminisces of
The locators were still undifferentiated (we do not know what John is remembering), but I think this worked better because the reader was still provided with some additional information about what type of information this was. I think the worst scenario for a long string of undifferentiated locators is to provide the reader with no context, so if all of the locators are similar in some way, it is worth adding a little extra to the entry.
The space constraint is really tight. Should I just delete all the subheadings?
No. Some subheadings will need to be deleted, but try to do this in a controlled, mindful manner. I like to call it performing triage on the index, which I have written about previously. Basically, my goal is to keep the most important entries as intact as possible, while making most of my cuts on the entries that are less important. Cutting this way will mean more entries with undifferentiated locators, but done right, a good number of subheadings should still be preserved and the reader should still be able to get a good sense of the book from the index.
Is there a magic formula for writing subheadings?
One of the problems with subheadings is that they take up a lot of real estate. So one temptation is to make subheadings as concise as possible. I value concision too, but I have come to value clarity more, even if it takes an extra word or two. Part of this is also making sure that the relationship between the heading and subheading is clear. If the reader cannot understand the entry, then the entry may as well be removed as it is not fulfilling its purpose.
I also try to write subheadings in plain language, alongside the author’s terminology. I don’t want to assume that the user of the index has already read the book or is familiar with the jargon, though this does vary from book to book, depending on the intended audience. For me, using plainer or simpler language is part of making the index accessible.
Do you mix subheadings with undifferentiated locators?
Ah, probably the most contentious question of them all. Personally, I do not like mixing subheadings with undifferentiated, or unruly, locators. Ask a handful of indexers what those orphaned locators signify and you will get a handful of different answers. If indexers can’t agree, I suspect readers will probably be confused too, so I’d rather have no subheadings than have a mix.
I do have two exceptions that I allow. The first is to start the entry with a broad range, such as for a whole chapter, which is then broken down in the subheadings. This tells the reader (I hope) that there is a significant chunk of text on the subject and if they want to start on the first page and read through, they can. The second scenario, which I may do if space is tight, is to leave locators for illustrations undifferentiated, though they would be indicated by the locator being in italics or boldface, for example, so they are still, in a way, differentiated.
But what about introductory material in the text? Does that really need to be broken down into subheadings?
Introductory material can be tricky to index, as it is usually brief and covers a lot of ground. This could be a paragraph per chapter in the introduction of the book, along with a couple of pages at the beginning of each chapter, as well as possibly a couple of pages at the end of each chapter, to sum up what has been discussed. I have heard some indexers say they leave these undifferentiated, with the assumption that readers will recognize this as introductory material. I don’t want to make that assumption, so I instead gather these into a subheading labeled something like, “about,” “approach to,” “introduction,” introduction and conclusion,” or “overview.” The exact wording varies according to what seems most appropriate for that particular text. I then force sort this subheading to the top of the entry, so readers can start with the introductory material, if they want.
What are some of the common questions or issues you face? Do you have different solutions to these problems? Feel free to reply and let me know.