Computer Book Index Style Guide

Computer books have some special conventions which often confuse even experienced authors, editors and copyeditors. Here are the answers to some common questions about these indexes.

Why don’t they use initial capitals for main entries?

Some special commands and application names need to be distinguished as such by using initial capitals for their names.

What do you do with special characters?

There are four basic options for listing non-alphabetical characters in an index.

Option 1 is a traditional one for computer books, and it uses the least space. Put entries beginning with numbers and/or symbols at the beginning of an index. Sort these entries in ASCII code order. (In ASCII code each special symbol is represented by a number made up of three digits. You don't see these three digit codes, but the computer sorts them in numerical order.)

Option 2 uses the most space, but the reader is more likely to find the entry sought. (Note: I know of no index usability studies that prove this. It is just conventional wisdom.) Put entries beginning with numbers and/or symbols at the beginning of the index AND put them inside the index too. Within the index list these entries as if their names were spelled out. If you use this option, it is redundant to list the entries in the separate section at the beginning of the index as if their names were spelled out. Use ASCII order for this initial section.

Option 3 is the standard practice for non-computer books and library catalogs. Put entries beginning with numbers and/or symbols inside the index only. List them as if their names were spelled out.

Option 4 is good only for a very brief list of special characters. Put entries beginning with numbers and/or symbols at the beginning of the index only. List them as if their names were spelled out.

Note: The last three options spell out names of numbers and symbols. Symbols may have more than one name, e.g. # is called pound key and number key. The indexer may need to "double post" the symbol under both names or make a "See cross-reference" from one name to the other.

Aren’t indexes supposed to be in alphabetical order?

As mentioned above, special characters may be sorted numerically in ASCII code order. This is very common practice. Note too that in computer books, things like standards or software versions may sometimes be listed in order by date of origin or numerically instead of alphabetically.

What about illustrations? How are those indexed?

Tables and figures are often an integral part of a computer book. ‘Locators’ or page numbers for illustrations are usually given in italic type. There can be different ways to use or not use italic locators for illustrations in a computer book. Here are some possibilities

(1) Assume that the reader will see an illustration on the page when they read the discussion about a topic. Use italic locators only for illustrations on a different page than the discussion.

zip drives, 112, 113, 156, 182

If you do this you should put an explanatory note at the beginning of the index telling the reader what the italic page numbers mean, e.g., "Page numbers in italics refer to illustrations that occur on pages that are separate from the discussion." (Note that index usability studies show that most readers don’t see these notes, but it is a traditional practice to put notes in the index...)

(2) Assume that readers may be looking up illustrations, and that they will not necessarily read the discussions. Use italic locators every time there is a table or figure indexed. This might look a bit redundant, but it tells the reader every page on which they can find an illustration.

zip drives, 112, 112, 113, 156, 182

If you do this, there should be an explanatory note at the beginning of the index telling the reader what italic page numbers mean, e.g., "Page numbers in italics refer to illustrations." (Note that index usability studies show that most readers don’t see these notes, but it is a traditional practice to put notes in the index...)

(3) You may choose to avoid the use of italic locators altogether by using subheadings such as <screen shot> or <illustration> to indicate where to find graphics in the book.

zip drives, 112, 156, 182
illustrations of 112,113

Here, no explanatory note at the beginning of the index is needed.

How much space should I leave for the index?

In her guide for indexers, Indexing Books, Nancy Mulvany explains how to determine the space needed for an index. She expresses index length as a ratio of index pages to book pages. Nancy explains that a 10 percent ratio is "not uncommon" for technical books and that some computer books have been known to have ratios of 20 to 25 percent. (See pages 63-67.)

On the other hand, such dense indexes in computer books can be a reflection of an indexer who doesn’t know computers and/or computer terminology. This type of indexer indexes every strange new word they see or every detail because they don’t know where the reader is likely to look!

You probably wonder how indexers make judgments about what to index and what not to index. So let’s take a hypothetical case. Let’s say that several ANSI standards are discussed on five contiguous pages. Is it necessary to list each standard by number in the index?

There is no one right answer to this question. It depends on the intent of the book. If your book is for certification, and the purpose of each standard must be known by the person taking a certifying test, the answer is definitely "yes."

If the index is an embedded index (using Word or Framemaker), the answer may again be "yes." That is because we don’t usually index page ranges in embedded indexes.

For all other cases, the answer is probably "no." When the answer is no, the index would show just one entry and a page range, e.g.,

ANSI standards for peripherals, 105-110.

Judging the amount of space to leave for an index is an art, and I will be covering this topic in more detail in my newsletter. As a general rule of thumb though, try to leave enough space for the indexer to index topics in detail if that is called for. If in doubt about how much space to leave, call and discuss space allotted for an index when the indexing process first begins—or even during the planning stage for the book.