Several typographic signs and symbols are frequently confused, and therefore misused, when setting type. Some of them are found in just about every typeface, while a few are less common. The confusion often arises when the provided text includes incorrect characters. In other instances, incorrect glyphs are inserted later in the design process. Ultimately, the responsibility for preventing, or catching and correcting, such typographic errors lies with the person setting and proofing the type.

Here are clarifications regarding some commonly confused typographic glyphs:

Inch and foot marks (primes) vs. smart quotes

When typesetting measurements, the proper indicators for inches and feet are primes, which in most fonts requires the use of aptly-named typewriter quotes. Unfortunately, when primes are called for, they often incorrectly appear as smart, or typographer's quotes, due to the commonly applied default setting in both word processing and design software. This default automatically replaces typewriter quotes with the smart variety, which are the typographically correct glyphs for setting quotation marks and apostrophes.

In the absence of a simple way to override this automatic software replacement, the best fix is to manually convert back to primes any smart quotes appearing in measurements. Primes are accessed via the glyph panel or character viewer.

Long s ligatures

A long s (also referred to as a medial or descending s) is a version of the lowercase s historically used when the letter appeared at the beginning or in the middle of a word. Although its use declined in the nineteenth century, the long s and its related ligatures are frequently found in historic typeface designs (Baskerville, Caslon, Garamond, etc.), as well as in those with classic roots and influences.

It is easy to confuse long s ligatures with the more common f ligatures due to the former's resembling the lowercase f, but without the right side of the crossbar. To compound the potential for misuse, some OpenType® fonts categorize long s glyphs as standard rather than discretionary ligatures. When intending to use f ligatures, be sure to select the proper f forms, and not the long s glyphs.

Mathematical symbols

Multiply symbol vs. the letter x: When typing measurements, most of us automatically type in the letter x for the multiply symbol. While this is fine for informal written communications, the correct typographical symbol is an actual multiply sign, found in most typefaces. The difference is that the glyph representing the letter x is design-sensitive, bearing the characteristics of the typeface, such as angle, weight contrast, serifs, etc. Conversely, the multiply sign is a simple, monostroke x, which can be accessed from the glyph panel or character viewer.

Minus symbol vs. hyphen or en dash: The design differences between the actual minus symbol and the hyphen or en dash frequently used in its place, are usually subtle, involving both length and vertical position (height relative to the baseline). Even so, it is always preferable to use the actual glyph intended for this mathematical operation, rather than the more easily accessed hyphen or en dash. The minus symbol, like the multiply symbol, can be accessed from the glyph panel or character viewer.

Forward slash vs. fraction bar

Although the forward slash and the fraction bar are both angled straight lines, they are different typographic forms with distinctly different purposes. The slash has several uses: as a substitute for the word or (morning/afternoon, Y/N); as part of an abbreviation (such as w/ for with); and sometimes to replace a hyphen or dash (chef/author/host). The fraction bar has been designed for one specific purpose: to separate the numerator and denominator in a diagonal fraction. As for design differences, the slash has a less extreme angle, and often extends below the baseline. It is frequently heavier than the fraction bar, which aligns with the baseline and cap height.

Setting automatic (diagonal) fractions (link to FT Fractions when posted) with an OpenType font begins with typing in the numbers manually, using a slash, which will be automatically replaced with the fraction bar during the conversion by OpenType fonts that have this feature. If manually creating diagonal fractions, the fraction bar can be accessed directly from the glyph panel or character viewer.

Ampersand (&) vs. the word and

The ampersand is a representation of the word and, but should not be used at random to replace the spelled out form when setting type. The ampersand is an appropriate substitution in certain instances, including: headlines and display settings, titles, branding and logos, citing sources in text (Brown & Brown), as well as connecting two related words in a list (jazz, classical, and rock & roll).

It requires far less time to prevent typographic mishaps from occurring than it takes to locate and correct them after the fact. It is helpful to inform everyone involved – designers and production artists, programmers and user interface specialists, writers, proofreads and editors – to be vigilant about these potential errors. As with every project, someone should proofread all text carefully before considering it final.

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• Editor’s Note:Ilene Strizver, founder of The Type Studio, is a typographic consultant, designer and writer specializing in all aspects of typographic communication. She conducts Gourmet Typography workshops internationally. Read more about typography in her latest literary effort, Type Rules! The designer's guide to professional typography, 4th edition, published by Wiley & Sons, Inc. This article was commissioned and approved by Monotype Imaging Inc.