The area structure

The area structure is conceptually one of nested boxes laid out with spaces around them and with formatting traits attached

There are two types of areas: block areas and inline areas

A line area is an example of a block are; a glyph area (for a "character") is an example of an inline area

The areas are separated by display space and inline space

The areas are placed within area containers (e.g., those corresponding to pages)

Areas have traits which are derived from the FO's properties (often directly, but sometimes via some computation)