They are internal placeholders created by PDF-exporting software when it fails to properly embed the original fonts.
While "F1" through "F7" can vary, they often correspond to these standard fonts or weights: Arial Bold Arial Regular F3 through F7 cid font f1 f2 f3 f4 f5 f6 f7 fonts free download link
: Because these are randomly generated labels, "F1" in one document might be Arial Bold, while "F1" in another could be Helvetica. Missing Data F1–F7 are not universal standards, but they are
Note: The exact mapping varies depending on the PDF creator. F1–F7 are not universal standards, but they are commonly reused across many documents. F1–F7 are not universal standards
Have a specific CID font not listed? Check the CMap resources inside your PDF using pdffonts command-line tool – then search for that exact BaseFont name.
Troubleshooting CIDFont F1–F7: Why You Can’t Just "Download" Them
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