Cell formatting is composed of several sets of properties:
Font properties (bold, italic, font color, font size, etc…)
Alignment properties (left, center, right alignment, etc…)
Border properties (left, right, top, bottom, thick or thin, color, etc…)
Number formatting properties (date, time, number of decimal places, etc…)
These properties, as a whole, describe how a particular cell is displayed and printed.
There are two types of objects that contain formatting properties. They are XFs (section 18.104.22.168) and DXFs (section 22.214.171.124). In general, XFs (section 126.96.36.199) describe the formatting directly associated with a cell, and DXFs (section 188.8.131.52) describe additional formatting properties that can be applied to one or more cells.