Text figures (also known as non-lining, lowercase, old-style, ranging, hanging, billing, or antique figures or numerals) are numerals typeset with varying heights in a fashion that resembles a typical line of running text, hence the name. They are contrasted with lining or titling figures, which are all of consistent height.
Design
In text figures, the shape and positioning of the numerals vary as those of lowercase letters do. In the most common scheme, 0, 1, and 2 are of x-height, having neither ascenders nor descenders; 6 and 8 have ascenders; and 3, 4, 5, 7, and 9 have descenders...