CHAPTER 4
382
Graphics
manipulate the state of optional content groups based on external factors such as
current system language settings or zoom level. Document authors can use
usage
application dictionaries
to specify which entries in the usage dictionary should be
consulted to automatically set the state of optional content groups based on such
factors. Usage application dictionaries are listed in the
AS
entry in an optional
content configuration dictionary (see Table 4.51). If no
AS
entry is present, states
are not automatically adjusted based on usage information.
A usage application dictionary specifies the rules for which usage entries should
be used by viewer applications to automatically manipulate the state of optional
content groups, which groups should be affected, and under which circumstanc-
es. Table 4.53 shows the entries in a usage application dictionary.
Note:
Usage application dictionaries are only intended for use by interactive viewer
applications, not for applications that use PDF as final form output (see “Determin-
TABLE 4.53 Entries in a usage application dictionary
KEY
TYPE
VALUE
Event
name
array
(Required)
A name defining the situation in which this usage application dictio-
nary should be used. May be
View
,
Print
, or
Export
.
(Optional)
An array listing the optional content groups that should have their
states automatically managed based on information in their usage dictionary
(see “Usage and Usage Application Dictionaries” on page 380). Default value: an
empty array, indicating that no groups are affected.
(Required)
An array of names, each of which corresponds to a usage dictionary
entry (see Table 4.52). When managing the states of the optional content groups
in the
OCGs
array, each of the corresponding categories in the group’s usage dic-
tionary should be considered.
OCGs
Category
array
The
Event
entry specifies whether the usage settings should be applied during
viewing, printing, or exporting the document. The
OCGs
entry specifies the set of
optional content groups to which usage settings should be applied. For each of
the groups in
OCGs
, the entries in its usage dictionary (see Table 4.52) specified
by
Category
are examined to yield a
recommended state
for the group. If all the
entries yield a recommended state of
ON
, the group’s state is set to
ON
; otherwise,
its state is set to
OFF
.