Why it will work in most cases it's not 100% accurate. According to PDF Reference: "Beginning with PDF 1.4, the version in the file header can be overridden by the Version entry in the document’s catalog dictionary".

>The PDF file is simply a text file. If you open one up using Notepad or any other text editor, you will find the first line to show the following:
>%PDF-x.x
>
>Where the x.x is the version number of the PDF document.
>
>So, you can read the first line of the PDF document using low-level file I/O to obtain it using VFP.