code: def _UTMLetterDesignator(Lat):
          
  
          if   84 >= Lat >= 72: return 'X'
          elif 72 >  Lat >= 64: return 'W'
          elif 64 >  Lat >= 56: return 'V'
          elif 56 >  Lat >= 48: return 'U'
          elif 48 >  Lat >= 40: return 'T'
          elif 40 >  Lat >= 32: return 'S'
          elif 32 >  Lat >= 24: return 'R'
          elif 24 >  Lat >= 16: return 'Q'
          elif 16 >  Lat >= 8:  return 'P'
          elif  8 >  Lat >= 0:  return 'N'
          elif  0 >  Lat >=-8:  return 'M'
          elif -8 >  Lat >=-16: return 'L'
          elif -16 > Lat >=-24: return 'K'
          elif -24 > Lat >=-32: return 'J'
          elif -32 > Lat >=-40: return 'H'
          elif -40 > Lat >=-48: return 'G'
          elif -48 > Lat >=-56: return 'F'
          elif -56 > Lat >=-64: return 'E'
          elif -64 > Lat >=-72: return 'D'
          elif -72 > Lat >=-80: return 'C'
          else:                 return 'Z'
docs: This routine determines the correct UTM letter designator for the given latitude
          returns 'Z' if latitude is outside the UTM limits of 84N to 80S
          Written by Chuck Gantz- chuck.gantz@globalstar.com