The terms F1, F2, F3, and F4 do not refer to specific font names (e.g., "Helvetica" or "Times New Roman"). Instead, they are or placeholders within a PDF's internal structure. According to the PDF specification, when a page's resource dictionary lists fonts, it often assigns them simple names like F1 , F2 , F3 , and F4 .
Or: /CMap /UniCNS-UTF32-H
You will usually encounter this error in three specific environments: cid font f1 f2 f3 f4
While this article focuses on F1 through F4, it's worth noting that the naming convention extends as far as needed – F5, F6, F7, and so on. However, F1 through F4 appear most frequently in documentation and error messages because: The terms F1, F2, F3, and F4 do