2.2.6.1.2.1 Cell Style XFs
A cell style XF is specified by an XF record (section 2.4.353) (and an optional XFExt record (section 2.4.355)) where the fStyle field of the XF record (section 2.4.353) equals 1. Each cell MUST reference a cell XF (section 2.2.6.1.1), and each cell XF (section 2.2.6.1.1) MUST reference a cell style XF with the ixfParent field.