Description: Under Disj , every block has a unique generator ( E* form). If t is a block in the quotient sense, then there is a uniquely determined u in dom R such that t = [ u ] R . This is the existence+uniqueness engine behind Disjs and QMap characterizations: it is the "representative theorem" from which the E! forms are obtained. (Contributed by Peter Mazsa, 5-Feb-2026)