Adobe ACROBAT READER 7.0 Manual page 167

Checking the accessibility of Adobe PDF documents
The Accessibility Quick Check feature quickly analyzes an Adobe PDF document for
accessibility and returns a brief statement of any accessibility issues. This feature
determines if the PDF document includes tags, if it's a scanned image (and therefore
inaccessible), or if it includes protection settings that prohibit access.
To check a PDF document using Accessibility Quick Check:
Choose Document > Accessibility Quick Check.
Note: If the document is unstructured, the checker may suggest that you change the
reading-order preference. (See Setting Reading preferences.)