Last week I wrote about internal consistency in an index, and how internal consistency can help make for a smoother user experience. But external consistency is also important, for the same reasons. The index should align with the text. 

Most obvious, of course, is alignment of content. The index should strive to neither misrepresent nor misinterpret the text, or in more extreme cases, neither ignore indexable content nor make up content. But that is not my main focus today. I am more concerned about formatting, term selection, and structure.

Spelling

One area for consistency is spelling. It is simple, yet for me, at least, easy to overlook, given how much I take certain spelling conventions for granted. As a Canadian, I usually run into this issue with American spelling in indexes for books published by American publishers and for Canadian books intended for an American audience. If I do not have a style sheet for the book and am not sure which is used, I will run a quick search for certain words which are commonly spelled differently. Spelling can be subtle, but I think alignment is still important to give the book a unified feel. At the very least, this saves the proofreader some work, if they are alert to this issue.

Locator Ranges

Locator ranges are another area for consistency. Some publishers have a preferred way to abbreviate (or not), while for other publishers it seems to vary from book to book. If you are not sure, check the bibliography or keep an eye out for ranges as you index.

Term Selection

Try to follow the text’s lead for names and terms. This can be tricky if the text itself is not consistent, but try to determine what is used most often and what the audience will be most familiar with. Cross references and double posts can also be used to add alternative entry points. We cannot assume that the reader has already read the book, but mirroring the terminology can make the index a bit easier to use for someone who has.

Structure

Following the book’s structure is not always good advice as the book may not have a clear structure or it may not be easy to mirror. So use your judgment and choose a structure that works best for the index. If the book’s structure is amenable, however, then be consistent in importing that structure. This will help the reader who has already read the book, and might help orient the reader who hasn’t. 

When considering external consistency, we are recognizing that the index is part of a larger whole. While the index has its own conventions, it also needs to take cues from the text that the index is pointing towards. The reader should be able to recognize that the index and the text belong together.

What are your thoughts on external consistency? Are there any areas that I missed?