Reading order and document structure tags are two important characteristics of accessible PDFs. The Reading Order command helps you easily check the reading order and edit tags for PDFs. However, the command is used to fix basic tagging problems for PDFs that were tagged with Foxit PDF Editor, not for PDFs that were tagged during conversion from an authoring application. If possible, try to return to the source file and add accessibility features in the authoring application.
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Foxit PDF Editor for Windows