A Contracting Party may apply the requirement referred to in subparagraph (a) only if it applied such requirement at the time of becoming party to this Treaty.
A Contracting Party may apply the requirement referred to in subparagraph (a) only if it applied such requirement at the time of becoming party to this Treaty.
唯有加入本条约时已实施（a）项所指要求的缔约方才可适用这种要求。