derived-mode-class

derived-mode-class is a compiled Lisp function in `derived.el'.

(derived-mode-class MODE)

This function is obsolete since 22.1;
use `derived-mode-p' instead.

Find the class of a major MODE.
A mode's class is the first ancestor which is NOT a derived mode.
Use the `derived-mode-parent' property of the symbol to trace backwards.
Since major-modes might all derive from `fundamental-mode', this function
is not very useful.