Mapping resources for PDF have a variety of functions, such as mapping CIDs
(Character IDs) to character codes, or mapping character codes to other
character codes.
These mapping resources for PDF should not be confused with CMap resources.
While both types of resources share the same file structure and syntax, they
have very different functions.
These PDF mapping resources are useful for some applications (e.g. Ghostscript)
to function properly.
