Writing Tips

Spacing (2)

Understanding the various types of spaces and their uses is typically a compositor's job. But in today's work world, where a writer may be composing or editing directly into a publishing system, it pays to know something about these tiny gaps in the fabric of your prose.

You may or may not be surprised to discover that there is more to spacing than pressing the spacebar on your composing system's keyboard. The various types of spaces that may be available to you include:

• Word space
• Hairline space
• Thin space
• En space ("figure space")
• Em space

Because HTML cannot show these different types of spaces, the examples in the discussion below use a "·" to mark the location of the space being considered.

The Word Space
The word space is typically generated by the spacebar on your composing system's keyboard. According to the Chicago Manual of Style, a word space normally occupies about one-third of an em (a measurement equal to about the width of the character "m" in the current font).

Most automated composing systems determine the size of a word space using internally coded rules for readability. If your lines of text are not fully justified, all word spaces will use this "normal" size.

In fully justified text, the composing system attempts to keep the word spaces at the "normal" size, but may uniformly shrink or expand all word spaces on each line (except the last) so that the starting and ending words exactly touch the left and right boundaries of the composed unit (e.g., paragraph). The shrinkage or expansion occurs within given tolerances. Depending on the sophistication of your composing system, you may be able to specify your preferred tolerances.

But beware! In some composing systems, shrinkage and expansion for justification are applied only to soft word spaces. These systems treat hard word spaces (see Spacing 1) not only as "unbreakable" but also as "unadjustable". In justified text, your hard word spaces may stand out as peculiarly wide or narrow when compared to the remaining soft word spaces on the same line.

The Hairline Space
Your composing system may provide a code for inserting a hairline space. Hairlines occupy the width of a "hair" (about one point) and should always be treated as hard spaces by a composing system.

The only conventional use for a hairline space is to separate the page number from the abbreviation n or nn when you are citing, as a source, an unnumbered note found on a particular page of a printed work. For example:

12. Marion Skate, My Life (New York: Manhattan Press, 1997), 75·n, 104·nn.

Otherwise, hairlines are used to make minute readability adjustments during final production of a text.

The Thin Space
If you produce a lot of information containing numbers for an international audience, you may want to ensure that your composing system provides a code for inserting thin spaces. Thin spaces are, by definition, slightly narrower than word spaces. They should always be treated as hard spaces by a composing system.

The conventional use for the thin space is to separate the digit groups in numbers expressed using the Système international d'unités (SI notation). The separator must appear in numbers of five digits or more, but is optional in numbers of four digits. It is also used in the decimal portion of the number. Here are some examples (where the dot indicates the thin space):

• The crowd at the rally numbered at least 10·000.
• Estimates of the crowd ranged between 7·500 and 15·000 people.
• Can you believe that Emily hand-addressed 2750 wedding invitations?
• The precision of that scale exceeds 0.000·001 gram.

The En Space
"En space" and "figure space" are names that often refer to the same type of space. The en space occupies about the width of the letter "n" in the current font. A figure space occupies exactly the same width as a figure (digit) in the current font. (All digits in a single font should be exactly the same width, usually about one en. Which explains why typing l997 ("el"997) instead of 1997 ("one"997) looks so peculiar.)

En or figure spaces are most often used to align columns of numbers set in a proportional font when zeros are inappropriate and such refinements as "align on decimal" are unavailable. Another use of the en space is to mark breaks in part numbers or other expressions where the unity of the whole needs to be balanced by emphasis on the constituent elements.

Most composing systems treat en spaces as hard spaces.

The Em Space
Em spaces occupy about the width of the letter "m" in the current font. The place where you are most likely to encounter them is in a table of contents. Some modern tables of contents place their page numbers immediately beside each section and subsection title, separated by one em space. You can use the em space in any similar situation: where you need to emphasize the separateness of two things, while still linking them. (The effect is exactly opposite to that of an en space. What a turnaround for such a small expenditure!)

Most composing systems treat em spaces as hard spaces.