I received some files from a third party that are supposed to be geoPDF. Is there a way to open a file (programmatically with .NET or Python, with a text editor, etc.) and verify it was created as a geoPDF? Does a geoPDF have bytes or an internal structure we can check?
On digitalpreservation.gov it says:
File signature /LGIDict A PDF file including GeoPDF encoding will be recognized by the existence of an LGIDict entry associated with at least one page in the PDF.
Presumably you'd need to use a PDF parser, iterate over the pages and look for the LGIDict entry. PDFMiner might be a good place to start (though I haven't used it).