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Why do the PDF-XChange products display the "File Info" of some PDF files in strange characters, whereas Adobe and other programs display readable information?


Why do the PDF-XChange products display the "File Info" of some PDF files in strange characters, whereas Adobe and other programs display readable information?

Please note that a user asked this question on the Tracker Software Products forum. They experienced an issue when they used our products to view the document properties of files that 'Bullzip' (and other free/cheap PDF products) had been used to create. The Author, Title, Producer and some other fields were not legible, whereas in Adobe Acrobat the information was correctly displayed.


This happens when escape strings are used in the XML metadata stream. To explain further: Adobe defined PDF specifications when they created the format, which the ISO (International Standards Organization) now maintains. They provide two methods to save extended document information, which is the data available to users when they view document properties. This information can be saved as either XML in a metadata stream, or within a "Document Information Dictionary." 

The PDF specifications dictate that data saved as XML in a metadata stream is hierarchically superior to data stored within a Document Information Dictionary. Therefore our products give the metadata stream superiority and use it to populate the Document Properties and File Information. 

However, when Ghostscript (and almost all products on which it is based, including Bullzip) is used to create PDF files, it adds a Document Information Dictionary as well as a metadata stream. Ghostscript uses escape strings to store information in the Document Information Dictionary and XML metadata stream. It is the use of escape strings in the XML metadata stream that causes file information problems, because it completely changes the set of values in XML format and they do not conform to the PDF specifications as a result.


Unfortunately there is no way to resolve this issue as we have a strict policy of adhering to the PDF specifications that the ISO specifies.

Further information on the PDF specifications and Ghostscript is available here.

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