Previous Next

                                                     876
       CHAPTER 10                                                             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     name          (Required) The attribute owner. Must be UserProperties.

P     array         (Required) An array of dictionaries, each of which represents a user property (see
                    Table 10.16).

       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     text          (Required) The name of the user property.

V     any           (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.

Previous Next