Adobe acrobat 7.0.5 sdk 用户手册

Creating PDF Documents

Creating a tagged document directly from an authoring application is the best way to make 
PDF documents accessible to screen readers and reflow correctly on handheld devices. 

If your PDF document was created without tags, Acrobat can add them. The tagging 
feature identifies most elements of a PDF document, including irregularly shaped columns, 
bulleted lists, captions that span columns, images that overlap text, and colored 
backgrounds.

From a plug-in, you can add structural information to any PDF file with the 

 API. 

Once a file has logical structure, 

 allows you to use it. For more information, see 

 and the Acrobat and PDF Library API 

Overview.

Advanced Acrobat features are generated using the pdfmark PostScript operator. The 
authoring application must generate a PostScript language file that contains the 
appropriate pdfmark operators for the document structure desired. This resulting 
PostScript language file is converted into a PDF file via Distiller. 

The pdfmark operator is not a standard PostScript operator, but is provided as a PostScript 
language extension used by Distiller to describe features that are present in PDF, but not in 
standard PostScript. The pdfmark operator has been available beginning with Distiller 3.0, 
and has evolved with each release of the PDF specification. 

While the pdfmark operator provides for greater extensibility, it is not intended to 
define every feature that is present in PDF but not in standard PostScript.

For more information, see the pdfmark Reference Manual and the PDF Reference.