paraph

paraph \PAR-uhf\, noun:

a flourish made after a signature, as in a document, originally as a precaution against forgery.

The manuscript's most tantalizing feature is a scribal paraph with the initials IB at the end of Certain sonnets...
-- H. R. Woudhuysen, Sir Philip Sidney and the Circulation of Manuscripts

His worried expression, however, was not just a mask for the moment. Of late, it had become his most distinctive feature, his peculiar paraph.
-- Ken Anderson, The Statue Of Pan

The paraph is only a schematic and marginal countersignature, a fragment of signature; indeed, who can claim to decipher a whole signature?
-- Jacques Derrida, Mémoires

Though early incarnations of paraph appear in Italian, Middle French, and Middle English, its earliest origins are Greek with para- meaning "beside" and the final -ph resulting from graphos, referring to text.