     fpakc     headr
     *    Convert the 5-digit number in )01&4 to a 3-character       )0D
     *    address in )02&2 using )03, which must be an index         )0D
     *    register.                                                  )0D
     *    Requires a word mark at )03-2.  Clobbers )03&1             )0D
     *                                                               )0D
               incldzonea
     )00       mn   )01&4,)02&2
               mn
               mn 
               za   )01+2,)03&1
               mz   zonel&)03,)02&2    Thousands / 4
               mz   zoneh&)03,)02      Thousands mod 4
