MONETARY FUND APPROVES WORLD CURRENCY MOVES;
IMF exec dirs approve new exch rate for dollar against major currencies to come into effect as soon as foreign exch trading resumes, even though Cong has not yet authorized tech increase in price of gold; dollar to continue to be 'unconvertible' when foreign exch mkts reopen; issue of eventual convertibility of dollar to be one of several that will be negotiated as part of gen reform of internatl monetary system and may become pressing issue fairly soon in light of strong Eur feelings
