SUM_AVE()

  Short:
  ------
  SUM_AVE() Interactive sum or average on a dbf field

  Returns:
  --------
  Nothing

  Syntax:
  -------
  SUM_AVE([cSumAve])

  Description:
  ------------
  Does a SUM or AVERAGE on a selected numeric field

  [csumAve] = "SUM" or "AVE". Default is "SUM"

  Examples:
  ---------
   case nChoice = 3  && sum

     SUM_AVE("SUM")

   case nChoice = 4  && average

     SUM_AVE("AVE")

  Notes:
  -------
  If sls_query() is not empty, an  optional SUM or
  AVERAGE for QUERY can be done.

  Source:
  -------
  S_SUMAV.PRG