Monogram

MONOGRAM. A character or cipher composed of one or more letters interwoven, being an abbreviation of a name.
     2. A signature made by a monogram would perhaps be binding, provided it could be proved to have been made and intended as a signature. 1 Denio, R. 471. And there seems to be no reason why such a signature should not be as binding as one which is altogether illegible. See Initial; Mark; Signature.