Notwithstanding subparagraph (1)(b), a Contracting Party may restrict the transfer of a Return in kind in circumstances where the Contracting Party is permitted under Article 29(2)(a) or the WTO Agreement to restrict or prohibit the exportation or the sale for export of the product constituting the Return in kind; provided that a Contracting Party shall permit transfers of Returns in kind to be effected as authorised or specified in an investment agreement, investment authorisation, or other written agreement between the Contracting Party and either an Investor of another Contracting Party or its Investment.