This feature replaces the default glyphs with corresponding forms designed specifically for titling. These may be all-capital and/or larger on the body, and adjusted for viewing at larger sizes.

Some fonts contain both a default form of zero, and an alternative form which uses a diagonal slash through the counter. Especially in condensed designs, it can be difficult to distinguish between 0 and O (zero and capital O) in any situation where capitals and lining figures may be arbitrarily mixed. This feature allows the user to change from the default 0 to a slashed form.