PDF glossary
CID font (Type 0)
A font format that uses multi byte codes, needed for large character sets like Chinese, Japanese and Korean, and common in modern exports.
Simple PDF fonts can address at most 256 glyphs. CID fonts, wrapped in a Type 0 composite font, address glyphs by two byte identifiers, so they can hold tens of thousands.
Many applications use CID fonts with Identity encoding for all text, even Latin, which is why their text is unreadable without a ToUnicode map.
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