[Editor’s note: This post refers and links to the 17th edition of CMOS.]

CMOS 6.119–21 in the Spotlight

To a copyeditor working on a manuscript, a space is usually just a space, and line breaks are random, fluid occurrences that vary as text is added and deleted and moved around. Designers and typesetters will take the edited text and make it pretty for publication, in part by applying different types of spaces as needed to prevent unwanted breaks.

Copyeditors can sometimes play a role, however, depending on a publisher’s workflow. At the very least, copyeditors (and proofreaders too) should know what to look for—and what’s practical to fix—when reviewing a document in its final format, whether in print or online.

All the spaces discussed in this post are available in both MS Word and Google Docs, so it’s easy for editors to learn about the different spaces and how they work.

Nonbreaking Spaces

The spaces in this sentence and throughout much of this post are sometimes called word spaces, because they appear between words. They’re the spaces you get when you hit the Space bar, and they allow for breaks at the ends of lines. (For end-of-line hyphenation, see CMOS 7.36–47.)

A nonbreaking space is a special type of space that prevents such breaks (see also CMOS 6.121). For example, nonbreaking spaces may be inserted in the following places (highlighted in red for easier identification):

1. Before and after the middle of three periods in a Chicago-style spaced ellipsis (. . .)
2. Between two or more initials in a name like “E. B. White”
3. Between single and double quotation marks (as in a “ ‘quote within a quote’ ”), or between a quotation mark and an apostrophe (as in the title of the song “Ain’t Misbehavin’ ”).
4. Between a numeral and an abbreviated unit of measure, as in “10 kg”

Each of these nonbreaking spaces prevents the characters immediately before and after the space from getting separated from each other at the end of a line. In the case of initials and abbreviated measurements, nonbreaking spaces are a nicety that some publishers observe only for print, if at all. And some publishers don’t add any space between consecutive quotation marks or between a quotation mark and an apostrophe. But the nonbreaking spaces are essential in spaced ellipses.

If you’re a copyeditor who’s been asked to apply such spaces where needed (or if you simply want to prevent your Chicago-style ellipses from breaking across a line), you can add a nonbreaking space in desktop versions of Microsoft Word by typing Ctrl+Shift+Space (Windows) or Option-Space (Mac).

Or in either Word or Docs, you can use the menu for special characters. In Word, go to Insert > Symbol and select “Nonbreaking Space” from the Special Characters tab:

In Docs, use the special characters menu to find and insert a “no-break space”:

But before you do that, start with a clean slate by getting rid of any nonbreaking spaces that may be lurking in random places in your document. In Word, enter “^s” in the Find box and a regular space in the Replace box. In Docs, use the Character Map (Windows) or the Character Viewer (Mac) to copy and paste a nonbreaking space into the Find box. Then either replace all or take a more cautious approach and go through them one by one.

Spaces are normally invisible, but in Word a regular space will show up as a dot (·) and a nonbreaking space as a circle (°) when you turn on formatting marks (by clicking the Show/Hide ¶ button on the Home tab). Or, among other tricks, you can select a space and use Insert > Symbol to discover which type it is. In Docs, the easiest option is to use Find.

Thin and Narrow Spaces

The regular nonbreaking space is defined for Unicode as the “no-break space,” or U+00A0. Unicode is the international text and emoji standard that’s used in virtually every modern application and device. And though most of us won’t ever need to know the codes, they can be helpful for finding characters that aren’t readily available from a keyboard.

The no-break space is like a regular space—that is, it’s the same width (but see next section)—except that it doesn’t break at the end of a line. Its nonbreaking behavior is reliable across applications and fonts and devices. And it’s easy to enter and use in word processors and in documents intended for publication in a variety of formats, from print to HTML (the usual format for web pages).*

But sometimes spaces of different widths are required. For example, some designers and typesetters use thin spaces (U+2009) in ellipses or between double and single quotation marks or apostrophes—a preference that’s usually limited to works published in print (or PDF). Thin spaces are typically added for publication in a page-layout program like Adobe InDesign, where they are nonbreaking by default.

And though the thin space—like any Unicode space—can be inserted using Word or Docs, the space to use for publication in online formats is the narrow no-break space, U+202F. That space, like the regular no-break space, can be depended on never to break, even in HTML viewed in a browser, where a thin space will normally break.

To get the narrow no-break space in Word, go to Insert > Symbol, and then enter character code 202F in the Symbols tab:†

More Spaces

The thin space and its narrow no-break cousin aren’t the only alternatives to the regular space. Unicode defines more than a dozen of them (including a few that take up no width). All of the following spaces, with the exception of the regular space and, usually, the no-break space, have fixed widths—that is, unlike those two spaces, they won’t get narrower or wider to fill out a line of justified text (text that aligns along both the left and right margins).‡ Each has been highlighted in red (following a regular space) to give an idea of relative width.

• space (U+0020):  . This is the space you get by hitting the Space bar.
• no-break space (U+00A0):  . The nonbreaking version of the Space bar space.
• narrow no-break space (U+202F):  . A nonbreaking space that can be used in place of a thin space.
• em space (U+2003):  . About the width of an em dash (—).
• en space (U+2002):  . About the width of an en dash (–), or half as wide as an em space.
• three-per-em space (U+2004):  . A third of an em space; also called a thick space.
• four-per-em space (U+2005):  . A fourth of an em space; also called a mid space.
• thin space (U+2009):  . A fifth (or sometimes a sixth) of an em space.
• six-per-em space (U+2006):  . A sixth of an em space.
• hair space (U+200A):  . Thinner than a thin space.
• figure space (U+2007):  . A nonbreaking space equal to the width of a tabular (monospaced) digit.
• punctuation space (U+2008):  . About the width of a period, colon, or exclamation mark.

Of these, only the no-break, narrow no-break, and figure spaces are nonbreaking across applications and formats, including HTML. However, all except the regular space are nonbreaking by default in InDesign and Google Docs; in current versions of Word, the en, em, and four-per-em spaces break, but the other fixed-width spaces do not.

The exact width of each space will vary a little from font to font, and any given font may lack some of these spaces. But most operating systems will take over as needed and substitute a font that does have the space.

* * *

It’s usually best to leave the fine-tuning of spaces to the design and typesetting stages, when they can be applied systematically and according to a publisher’s design specs. Copyeditors, unless directed otherwise, should avoid adding anything other than Space bar spaces and their regular nonbreaking equivalent during editing (and never two spaces in a row). But a knowledge of other types of spaces and how they work can help everyone make sure their documents are ready for publication.

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* In HTML, the regular nonbreaking space is “nbsp” (and represented in HTML markup as  ).

† The codes for these and other characters can be looked up using the Unicode Character Name Index.

‡ The no-break space has a fixed width in current versions of Word and Docs. But in other environments, including HTML and InDesign, its width in text with full justification is variable by default.

Top image: Earthrise (December 24, 1968), NASA.

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