FLC OF B747-400 UNABLE TO CLARIFY REASON FOR NOT ACCEPTING A CLB CLRNC WITH SPD RESTR DUE TO LANGUAGE BARRIER.

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WHILE ENRTE SEOUL; KOREA; TO SFO AND IN JAPANESE AIRSPACE; WE RECEIVED A MACH NUMBER RESTR FOR MACH .84 AT FL330. SINCE OUR PLAN CALLED FOR MACH .86 AND MACH .84 WOULD RESULT IN HIGHER FUEL BURN AND TIME ENRTE; WE REQUESTED FL350 AT MACH .86; BUT TOKYO CTL RESPONDED UNABLE DUE TFC. WHEN TOKYO CTL HANDED US OFF TO TOKYO RADIO; WE AGAIN REQUESTED FL350 AT MACH .86; BUT WERE AGAIN DENIED. LATER WE RECEIVED A CLRNC FROM TOKYO RADIO TO CLB TO FL350 AND MAINTAIN MACH .84. WE DECLINED THE CLRNC EXPLAINING WE DID NOT WANT FL350 UNLESS WE COULD MAINTAIN MACH .86 AND WE WOULD MAINTAIN MACH .84 AT FL330. TOKYO RADIO RESPONDED WITH; ROGER; MAINTAIN MACH .84. AT OUR NEXT POS RPT; TOKYO RADIO QUESTIONED OUR ALT FL330 AND ASKED IF WE RECEIVED A CLRNC TO FL350. OUR RESPONSE WAS TO EXPLAIN ONCE AGAIN OUR REQUIREMENT FOR HIGHER MACH .86 AT FL350; AND MACH .84 ONLY AT FL330; AS WE PREVIOUSLY EXPLAINED. AFTER SOME DELAY; TOKYO RADIO RELAYED THE CLRNC TO MAINTAIN MACH .84 AT FL330. APPARENTLY OUR ORIGINAL REJECTION OF THIS CLRNC WAS MISUNDERSTOOD BY THE JAPANESE RADIO OPERATOR AND THEN MISCOMMUNICATED OUR INTENTIONS TO TOKYO CTL. ASSUMING WE WOULD CLB TO FL350 AS REQUESTED AND MAINTAIN MACH .84 WE FELT WE USED CARE IN COMMUNICATING WITH THE JAPANESE RADIO OPERATOR; BUT IT IS EVIDENT WE SHOULD HAVE BROKEN THE REJECTION INTO 3 PARTS -- IE; 1) UNABLE MACH .84 AT FL350. 2) MAINTAINING MACH .84 AT FL330. 3) REQUEST MACH .86 CRUISE. THIS MIGHT HAVE MORE CLRLY DEFINED OUR INTENTIONS AND BETTER EXPRESSED OUR CRUISE CONCERNS. WE NEED BETTER USE OF OCEANIC AIRSPACE TO AVOID CRUISE RESTRAINT CONFLICTS BTWN ACFT OPERATING NORMALLY AT HIGHER AND LOWER SPDS. THIS WOULD BE POSSIBLE IF WE WERE ALLOWED USE OF OUR FANS NAV SYS. FURTHERMORE; USE OF DATA LINK/DIRECT LINE COMS IN FOREIGN AIRSPACE REDUCES CONCERNS FOR MISINTERP DUE TO LANGUAGE CONSTRAINTS. BOTH WOULD BE POSSIBLE BUT FOR GOVERNMENTAL RESTRAINT IN THE USE OF THESE AIDS.