S2 was designed from the ground up to allow a much-increased level of flexibility when customizing your journal. Because of this, the structure of a custom style in S2 is different from that of S1.
S2 styles are composed of "layers". Each layer in a S2 style deals with a different aspect of the style, including color, translation, and HTML options and settings. A complete S2 style is the result of putting its different layers together for use.
→ See a basic list of definitions that are used in S2