face-spec-set

face-spec-set is a compiled Lisp function in `faces.el'.

(face-spec-set FACE SPEC &optional SPEC-TYPE)

Set the face spec SPEC for FACE.
See `defface' for the format of SPEC.

The appearance of each face is controlled by its specs (set via
this function), and by the internal frame-specific face
attributes (set via `set-face-attribute').

This function also defines FACE as a valid face name if it is not
already one, and (re)calculates its attributes on existing
frames.

The argument SPEC-TYPE determines which spec to set:
nil or `face-override-spec' means the override spec (which is
usually what you want if calling this function outside of
Custom code);
`customized-face' or `saved-face' means the customized spec or
the saved custom spec;
`face-defface-spec' means the default spec
(usually set only via `defface');
`reset' means to ignore SPEC, but clear the `customized-face'
and `face-override-spec' specs;
Any other value means not to set any spec, but to run the
function for its other effects.