MERGE FIELDS=(25,7,A,1,10,D),FORMAT=CH
 OPTION CHALT
 ALTSEQ CODE=(F0B0,F1B1,F2B2,F3B3,F4B4,F5B5,F6B6,
      F7B7,F8B8,F9B9)

The numerals 0 through 9 are to collate before uppercase letters (but after lowercase letters).