documentation-property

documentation-property is a built-in function in `C source code'.

(documentation-property SYMBOL PROP &optional RAW)

Return the documentation string that is SYMBOL's PROP property.
Third argument RAW omitted or nil means pass the result through
`substitute-command-keys' if it is a string.

This differs from `get' in that it can refer to strings stored in the
`etc/DOC' file; and that it evaluates documentation properties that
aren't strings.