GREP in InDesign

Look Behind

In addition to looking ahead, you can also look back (or “behind,” as it’s called in the world of GREP). There are two formats for positive lookbehind: (?<=) and \K. The former, (?<=), is the classic lookbehind generally available in GREP implementations, and was present when GREP was added to InDesign in CS3. \K was introduced in CS6, is easier to use, and is more efficient, but for the sake of compatibility with pre-CS6 versions of InDesign we illustrate both formats here.

Italicize Prefixed Words

For example, to italicize all words with the prefix over but not that prefix itself, do this:

Find what:	(?<=over)\w+ or over\K\w
Change to:	<leave blank>
Change format:	Italics

Italicize Letters Following a Year

For another example, we turn again to bibliographies. When an author has more than one publication in one year, these publications are distinguished by placing a letter after the year (2007a, 2007b, 2007c, etc.) Many publishers want these letters italicized. To find them, all we need to do is formulate a lookbehind to match four digits:

Find what:	(?<=\d\d\d\d)[a-z] or \d\d\d\d\K[a-z]
Change to:	<leave blank>
Change format:	Italics

We could have used \l (for “any lowercase letter”) instead of [a-z]—it doesn’t make any difference.

Use Table Figures After Capitals

In a text that uses oldstyle figures by default, it is often better to use lining figures in combination with capitals, as in C8 and DK23. To find numbers preceded by a capital and apply ...