; and (II) significant nonblanket licensees; and (ii) voluntary contributions from digital music providers and significant nonblanket licensees as may be agreed with copyright owners. (B) Voluntary contributions (i) Agreements concerning contributions Except as provided in clause (ii), any voluntary contributions by digital music providers and significant nonblanket licensees shall be determined by private negotiation and agreement; provided, however, that— (I) the date and amount of any voluntary contribution to the mechanical licensing collective shall be documented in a writing signed by an authorized agent of the mechanical licensing collective and the contributing party