Kerning

In typography, kerning, or less commonly, mortising (referring to the process of physically removing material from the cast character), is the process of adjusting letter spacing in a proportional font. In a well-kerned font, the two-dimensional blank spaces between each pair of letters all have similar area.
Kerning pairs
In digital typography, kerning is usually applied to kerning pairs as a number to be added to the default character spacing, expressed in the font's coordinate system. For example, the kerning of VA in Adobe's Helvetica font is -80. A digital font's kerning feature can also increase the character spacing between two characters; for example the kerning value for ry in Adobe's Helvetica is 30. Increased character width is used mainly in conjunction with accented letters.
DocFamily supports the kerning feature in the formatting step (XSL-FO to Intermediate Format).