A page is made up of five area regions. These are before, start, body,
end and after. Each region has a viewport and contains the areas
produced from the children in the FO object heirarchy.
For the body area there are more subdivisions for before floats,
footnotes and the main reference area. The main reference area is
made from span areas which have normal flow reference areas as
children. The flow areas are then created inside these normal flow
Since the layout is done inside a page, the page is created from the
pagemaster with all the appropriate areas. The layout manager then
uses the page to add areas into the normal flow reference areas
and floats and footnotes. After the layout of the body region
is complete then the other regions can be done.