Logical Structure in PDF
How to view logical structure
To view the logical structure in a PDF document (if available) you need to display the “Tags” panel. This can be found under (View – Navigation Tabs – Tags) in Acrobat 6.0 Professional and (View – Tabs in Acrobat 5.0).Structure insertion using XML templates
– Download unstructured PDF – Download structured PDF 
– Download XML version
These 3 files are representations of the same document. The XML file can be viewed as the notional starting point for the document-processing pipeline from which the unstructured PDF file may have been produced. The structured PDF file was produced by processing the XML file and the unstructured PDF to create a fully structured PDF. These techniques are described Matthew Hardy in his PhD thesis.
Mathematical Structure and alternate readings
– Download unstructured PDF – Download structured
PDF – Download MathML version
The quadratic expression has been typeset using LaTeX to produce an unstructured PDF file, this PDF file was altered by inserting a structure tree corresponding to the MathML (also available to download). Furthermore, an English-text rendition of the expression was inserted into the structure tree so that the structured version is read-aloud correctly. Contrast this with how the unstructured version (no alternate reading) is read aloud. To read a PDF document aloud in Acrobat 6.0 select (View – Read out loud)