First, it is necessary to establish the foundational concept of a CID-keyed font. Unlike traditional fonts that rely on a single-byte encoding (e.g., ASCII for Latin fonts), a CID font separates the character collection from the glyph descriptions. A is a number that identifies a character, not its visual representation. A CMap (Character Map) then translates between an external encoding (like Shift-JIS or Unicode) and these internal CIDs. The "F" designators—F1 through F4—are specific data structures or processing states within the Adobe Type Manager and PostScript rendering engines that facilitate this mapping and glyph retrieval process.
The nomenclature is not a bug or a corruption. It is a feature of the PDF specification that allows complex multilingual documents to remain structured and efficient. The F stands for "Font resource," and the number is simply the order of appearance. cid font f1 f2 f3 f4
: In many cases, these placeholders refer to standard system fonts that failed to embed: First, it is necessary to establish the foundational
7 0 obj % The actual font object for F1 << /Type /Font /Subtype /Type0 % CID-keyed font container /BaseFont /AdobeMingStd-Light /Encoding /Identity-H % Horizontal writing, direct CID mapping /DescendantFonts [8 0 R] % Points to the CIDFont dictionary /ToUnicode 9 0 R % For text extraction >> endobj A CMap (Character Map) then translates between an
Modern browsers handle F1-F4 tags gracefully as long as the font is embedded. However, browsers prioritize . If your PDF relies on F1 as a Type 0 (PostScript), the browser may fall back to a default sans-serif for that specific tag, breaking your layout.
| Problem | Likely Cause | Solution | | :--- | :--- | :--- | | Text shows as random dots/boxes | Printer F1 font lacks a required CID | Embed the full CID font in the PDF (do not rely on printer fonts). | | "Undefined CID" error | F2 font (Chinese) is being used for Korean text (F4) | Correct the CMap in the source document (e.g., InDesign or Acrobat). | | Slow printing | Printer is swapping between F1, F2, F3, F4 on every page | Optimize PDF: embed one CID font subset instead of switching encodings. |