A maps individual character shapes (glyphs) to numeric identifiers rather than specific character names. This framework, originally designed by Adobe to handle complex East Asian languages, is highly efficient for embedding font subsets in PDF files.
: Names like "F1" or "F2" are often assigned by PDF creation software (like InDesign or Word) when it embeds a subset of a font.
The labels F1 through F4 are simply an index used by the PDF to distinguish between different fonts or styles used in the same file. While they vary by document, common patterns observed in software exports include:
, which is better at handling complex languages like Chinese, Japanese, or Korean (CJK) by allowing up to 65,535 separate characters instead of the standard 256. Why You Encounter Errors cid font f1 f2 f3 f4 better
This is one of the most common and disruptive errors in digital document management. It disrupts workflows, halts legal signings, and ruins presentations.
These names act as placeholders for the actual fonts used in the original document. Often, they map to standard fonts like Times New Roman in different styles: : Often represents the : Often represents the : Usually assigned to other weights or styles, such as Bold Italic Why You See These Labels
Sometimes a specific placeholder (like F2) may trigger an error stating it "does not contain all required characters," making the others more reliable for that specific file. A maps individual character shapes (glyphs) to numeric
Uncheck "Subset fonts when percent of characters used is less than..." or force . Final Verdict
| Attribute | F1 | F2 | F3 | F4 | |---|---:|---:|---:|---:| | Glyph coverage | Often full set | Subset optimized | Full with hinting | Subset + optimized enc | | File size | Largest | Small | Large | Smallest | | Rendering sharpness | Good | Adequate | Best (hinted) | Good | | Compatibility | High | High | High | High | | Best for | Print, archival PDFs | Web or lightweight PDFs | Screen-readable PDFs, small-text clarity | Low-bandwidth or web use | | Typical use-case | Archival, exact glyphs | Faster downloads | UI text, small sizes | Mobile/embedded PDFs |
You typically encounter these names when opening a PDF in a vector editor (like Illustrator) that doesn't have the original fonts installed. The software sees the embedded "CID" data—which is excellent for cross-platform rendering and supporting complex character sets—but cannot identify the specific local font file to allow editing. Quick Fixes for "Better" Results The labels F1 through F4 are simply an
When a PDF creator embeds only a subset of a CID font, the F1 label persists even though half the glyphs are missing. This leads to the dreaded "dots" or "blank squares" for missing characters.
Unlike simple fonts (Type 1 or TrueType) that map a single byte to a glyph, CID fonts are designed for large character sets. A CID font separates the (the set of glyphs) from the CMAP (character map). The PDF specification uses numeric labels—often F1, F2, F3, F4 —as font aliases or internal names for these CID-keyed fonts when the original font name is missing or when subsetting occurs.
