AUTO
   REM Is% a non-proleptic Gregorian year y$<=9999 leap (0) 0R ordinary (1)?
   DEF FN Is%(y$)
     LOC l%,c%,y%
     LET c%=y$(1 TO 2)&"00" : y%=y$
     LET l%=c% MOD 16 AND y$(3 TO 4)="00" OR y% MOD 4
     RET l%
   END DEF Is%
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