SECTION 8.4
619
Anno ta tions
KEY
TYPE
VALUE
Subj
text string
name
(Optional; PDF 1.5)
Text representing a short description of the subject being
addressed by the annotation.
(Optional; meaningful only if
IRT
is present; PDF 1.6)
A name specifying the rela-
tionship (the “reply type”) between this annotation and one specified by
IRT
. Val-
id values are:
R
RT
The annotation is considered a reply to the annotation specified by
IRT
. Viewer applications should not display replies to an annotation
individually but together in the form of threaded comments.
The annotation is grouped with the annotation specified by
IRT
; see
discussion below.
Group
Default value:
R
.
IT
name
(Optional; PDF 1.6)
A name describing the
intent
of the markup annotation. In-
tents allow viewer applications to distinguish between different uses and behav-
iors of a single markup annotation type. If this entry is not present or its value is
the same as the annotation type, the annotation has no explicit intent and should
behave in a generic manner in a viewer application.
Free text annotations (Table 8.25), line annotations (Table 8.26), polygon anno-
tations (Table 8.29), and (in PDF 1.7) polyline annotations (Table 8.29) have de-
fined intents, whose values are enumerated in the corresponding tables.
ExData
dictionary
(Optional; PDF 1.7)
An
external data dictionary
specifying data to be associated
with the annotation. This dictionary contains the following entries:
Type
(optional):
If present, must be
ExData
.
Subtype
(required):
a name specifying the type of data that the markup anno-
tation is associated with. In PDF 1.7, the only defined value is
Markup3D
.
For each value of
Subtype
, other entries are defined. Table 9.48 on page 835
lists the values that correspond to a subtype of
Markup3D
. (See also
implementation note 96 in Appendix H.)
In PDF 1.6, a set of annotations can be grouped so that they function as a single
unit when a user interacts with them. The group consists of a
primary annotation,
which must not have an
IRT
entry, and one or more
subordinate annotations,
which must have an
IRT
entry that refers to the primary annotation and an
RT
en-
try whose value is
Group
.
Some entries in the primary annotation are treated as “group attributes” that
should apply to the group as a whole; the corresponding entries in the subordi-