At2()

         Looks for the Nth occurrence into an string

    Syntax:

         At2( cSearch, cTarget [, nOcur] ) -> nPos

    Description:

         The parameters are the same than AT() of the standard library
         Cliper.lib except for nOcur that indicates de number of the
         occurrence to return. The default nOcur is 1.
         The function is Case Sensitive.

    Return:

         The same than AT().

    Example:

         ? At2 ( "a", "Manu Roibal" )      //  2
         ? At2 ( "a", "Manu Roibal", 2 )   // 10
         ? At2 ( "a", "Manu RoibAl", 2 )   // 0