The positioning of display areas is specified by area
containers. An area container has its own coordinate system with its
origin at the lower left corner, the positive x-axis extending
horizontally to the right and the positive y-axis extending vertically
An area container has a filling-direction specified in
terms of its own coordinate system.
The filling-direction gives a
starting edge and an ending edge which are opposite to each other.
The size of an area container is always fixed in the direction
perpendicular to the filling-direction. This means that the lengths
of the starting and ending edges are always fixed and equal to each other.
The size of an
area container in the filling-direction may be fixed or it may be
specified to grow as necessary to contain the areas with which it is
filled. The display areas with which an area container is filled are
always created so that their size in the direction perpendicular to
the filling-direction is equal to the size of the area container in
direction. This is called the display-size of the area. An
area container is filled with a sequence of display areas as follows.
The first display area is positioned with its starting edge aligned
with the area container's starting edge. The next display area is
then positioned with its starting edge on the previous area's ending
edge, and so on. This is illustrated in Figure 5, Area Containers and
An area container resulting from an included-container-area flow object
may also specify a rotation to be
applied to each of the display areas with which it is to be filled.
The angle of rotation is restricted to be a multiple of 90 degrees.
This rotation is applied to each display area, thus changing the
display area's starting and ending edges.
The direction between a
display area's starting and ending edges is the placement
direction of the display area.
A display area also has an associated writing-mode that is
perpendicular to the area's placement direction. This is illustrated
in Figure 6, Placement Direction for