Glossary E

ear

A stroke extending from the upper part of the lowercase g in some typefaces.

Egyptian

See square serif.

em

A typographic unit of measure whose dimensions are relative (with no fixed value) and equal to the square of any size of a typeface. For example, in 10-point type, the em measures 10 points high by 10 points wide. At 100 points it is 10 times as large, measuring 100 points by 100 points. Traditionally the height of the em is equivalent to the body. The em is often used by type designers and manufacturers as a basic unit of measurement in type design and production; it also serves as the basis for unit systems of typeface measurement. In photo- and digital typesetting, compositors often use the em mainly for measurements in the horizontal direction (linear measure). Such measurements typically apply to spaces, indents, and characters such as rules.

In the past some type manufacturers commonly defined the em as a variable dimension derived from the width of the typeface. In a typeface with narrow forms, the em was narrower than the point size; in a typeface with wide forms, the em was wider than the point size. (In both of these usages, the em was not truly square but rectangular, because its height did not change.) According to tradition, the term is derived from the capital M (usually the widest letter, after W), which in some typefaces occupies a full em square or a width similar to the em square. See also body, em space.

em fraction

See diagonal fraction.

em space

A space equal to the measure of the em at a given point size. In composition with metal type, it was created by the em quad, a block of type that was less than type high so that it would not print. Compositors and printers sometimes called the em quad mutton or molly, to distinguish it from the en quad. Em quad is a synonym. See also body, em.

em square

See em.

en

A relative typographic unit of measure (with no fixed value) equal to one-half the width of the em or half the type size. Tradition holds that the en derived its name from the lowercase n, which in some typefaces occupies a space approximately as wide as the en. See also em, en space.

en fraction

See horizontal fraction.

en space

A space equal to the measure of the en at a given point size. In composition with metal type, it was created by the en quad, a block of type that was less than type high so that it would not print. Compositors and printers sometimes called the en quad a nut, to distinguish it from the em quad. En quad is a synonym. See also en.

Ep height

See Hp height.

Êp height

The distance from the top of the tallest accented capital letter to the bottom of the lowest descender in a typeface. Because this distance often exceeds the height of the typeface body, it is used by some compositors in determining the minimum amount of space that must be added between lines of type to prevent the overlap of accented capital letters with descenders from preceding lines. See also body.

escapement

See width.

expanded

Most commonly describes typefaces that appear wider than other variants within the same family, the opposite of condensed. Some expanded typeface variants are known as extended. See also typeface width.

extended family, extended typeface family

See typeface family.

extreme

In computer-aided type design, a point that is the highest, lowest, leftmost, or rightmost point of a character or character part. From the mathematical term extremum (plural extrema).