cid – Fonts defined by character identifier
CID-keyed fonts were developed by Adobe to handle character sets containing large numbers of glyphs, notably for East Asian languages (Chinese, Japanese, Korean, etc.). The glyphs are addressed by number rather than name, and organized into so-called collections.
See the Wikipedia entry, among other places, for more information.
Maybe you are interested in the following packages as well.
- stix: OpenType Unicode maths fonts
- marcellus: Marcellus fonts with LaTeX support
- arvo: The Arvo font face with support for LaTeX and pdfLaTeX
- gudea: The Gudea font face with support for LaTeX and pdfLaTeX