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          CHAPTER 8                                                             Interactive Features




                      TABLE 8.38 Additional entries specific to a screen annotation
KEY         TYPE             VALUE

Subtype     name             (Required) The type of annotation that this dictionary describes; must be Screen
                             for a screen annotation.

T           text string      (Optional) The title of the screen annotation.

MK          dictionary       (Optional) An appearance characteristics dictionary (see Table 8.40). The I entry
                             of this dictionary provides the icon used in generating the appearance referred
                             to by the screen annotation’s AP entry.

A           dictionary       (Optional; PDF 1.1) An action to be performed when the annotation is activated
                             (see Section 8.5, “Actions”).

AA          dictionary       (Optional; PDF 1.2) An additional-actions dictionary defining the screen anno-
                             tation’s behavior in response to various trigger events (see Section 8.5.2, “Trigger
                             Events”).

          In addition to the above entries, screen annotations use the common entries in
          the annotation dictionary (see Table 8.15) in the following ways:

          • The P entry is required for a screen annotation referenced by a rendition ac-
            tion. It must reference a valid page object, and the annotation must be present
            in the page’s Annots array for the action to be valid.
          • The AP entry refers to an appearance dictionary (see Table 8.19) whose normal
            appearance provides the visual appearance for a screen annotation that is used
            for printing and default display when a media clip is not being played. If AP is
            not present, the screen annotation has no default visual appearance and is not
            printed.


          Widget Annotations

          Interactive forms (see Section 8.6, “Interactive Forms”) use widget annotations
          (PDF 1.2) to represent the appearance of fields and to manage user interactions.
          As a convenience, when a field has only a single associated widget annotation, the
          contents of the field dictionary (Section 8.6.2, “Field Dictionaries”) and the anno-
          tation dictionary can be merged into a single dictionary containing entries that
          pertain to both a field and an annotation. (This presents no ambiguity, since the
          contents of the two kinds of dictionaries do not conflict.) Table 8.39 shows the

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