CHAPTER 10
876
Document Interchange
User Properties
Most structure attributes (see Section 10.7.4, “Standard Structure Attributes”)
specify information that is reflected in the element’s appearance; for example,
BackgroundColor
or
BorderStyle
. However, some PDF producers, such as CAD
applications, may use objects that have a standardized appearance, each of which
contains non-graphical information that distinguishes the objects from one an-
other. For example, several transistors might have the same appearance but dif-
ferent attributes such as type and part number.
User properties (PDF 1.6)
can be used to contain such information. Any graphical
object that corresponds to a structure element may have associated user proper-
ties, specified by means of an attribute object dictionary with a value of
UserProperties
for the
O
entry (see Table 10.15).
TABLE 10.15 Additional entries in an attribute object dictionary for user properties
KEY
TYPE
VALUE
O
P
name
array
(Required)
The attribute owner. Must be
UserProperties
.
(Required)
An array of dictionaries, each of which represents a user property (see
The
P
entry is an array specifying the user properties. Each element in the array is
a
user property dictionary
representing an individual property (see Table 10.16).
The order of the array elements is significant, allowing producers to specify at-
tributes in order of importance.
TABLE 10.16 Entries in a user property dictionary
KEY
TYPE
VALUE
N
V
text
any
(Required)
The name of the user property.
(Required)
The value of the user property.
Note:
While the value of this entry is allowed to be any type of PDF object, PDF producers
are strongly encouraged to use only text string, number, and boolean values. PDF consumers
are not required to display values of other types to users; however, they should tolerate other
values and not treat them as errors.
F
text string
(Optional)
A formatted representation of the value of
V
, used when special formatting is
required; for example “($123.45)” for the number -123.45. If this entry is absent, applica-
tions should use a default format.