SECTION 10.7
931
Tagged PDF
The allocation rectangle is derived from the content rectangle in a way that also
depends on the structure type:
•
For a BLSE, the allocation rectangle is equal to the content rectangle with its
before and after edges adjusted by the element’s
SpaceBefore
and
SpaceAfter
attributes, if any, but with no changes to the start and end edges.
•
For an ILSE, the allocation rectangle is the same as the content rectangle.
Note:
Future versions of Tagged PDF are likely to include additional attributes that
can adjust all four edges of the allocation rectangle for both BLSEs and ILSEs.
Illustration Attributes
Certain additional restrictions arise in connection with particular uses of illustra-
tion elements (structure types
Figure
,
Formula
, or
Form
):
•
When an illustration element has a
Placement
attribute of
Block
, it must have a
Height
attribute with an explicitly specified numerical value (not
Auto
). This
value is the sole source of information about the illustration’s extent in the
block-progression direction.
•
When an illustration element has a
Placement
attribute of
Inline
, it must have a
Width
attribute with an explicitly specified numerical value (not
Auto
). This
value is the sole source of information about the illustration’s extent in the
inline-progression direction.
•
When an illustration element has a
Placement
attribute of
Inline
,
Start
, or
End
,
the value of its
BaselineShift
attribute is used to determine the position of its af-
ter edge relative to the text baseline;
BaselineShift
is ignored for all other values
of
Placement
. (An illustration element with a
Placement
value of
Start
can be
used to create a dropped capital; one with a
Placement
value of
Inline
can be
used to create a raised capital.)