S E C T I O N H .3
1125
Implementation Notes
157. Acrobat viewers earlier than version 7.0.7 did not honor the
U3DPath
en-
try of a 3D view dictionary. Acrobat 7.0.7 supports text string values for
this entry and deprecates the use of an array for its value.
158. PDF 1.7 introduced several new dictionaries for controlling the appear-
ance and behavior of 3D artwork and for enabling markup annotations on
3D views. Although Acrobat 7.0 officially supports PDF 1.6, Acrobat 7.0.7
also supports these new dictionaries.
159. Acrobat viewers earlier than version 5.0 respond to requests for unknown
procedure sets by warning the user that a required procedure set is un-
available and canceling the printing operation. Acrobat 5.0 ignores proce-
dure sets.
160. Acrobat viewers display the document’s metadata in the Document Prop-
erties dialog box and impose a limit of 255 bytes on any string represent-
ing one of those values.
161. For backward compatibility, applications that create PDF 1.4 documents
should include the metadata for a document in the document information
dictionary as well as in the document’s metadata stream. Applications that
support PDF 1.4 should check for the existence of a metadata stream and
synchronize the information in it with that in the document information
dictionary. The Adobe metadata framework provides a date stamp for
metadata expressed in the framework. If this date stamp is equal to or later
than the document modification date recorded in the document informa-
tion dictionary, the metadata stream can be taken as authoritative. If, how-
ever, the document modification date recorded in the document
information dictionary is later than the metadata stream’s date stamp, the
document has likely been saved by an application that is not aware of PDF
1.4 metadata streams. In this case, information stored in the document in-
formation dictionary should be taken to override any semantically equiva-
lent items in the metadata stream.