Scan16()

         Looks for an element of an array16

    Syntax:

         Scan16 ( aArray, xSearch [, nStart] ) -> nPos

         aArray  : The previously created array16
         xSearch : The value to look for into the array
         nStart  : The initial value of the position to start the looking for.
                   Is taken by defect from the first element

    Description:

         Looks for an element into an array16 and returns its position
         if can find it.

    Return:

         The position where the element to look for is or 0 if it can not
         be found into the array16.

    Example:

         a16 := New16 ( 15000, 0 )
         Add16 ( a16, 1 )
         ? Len16 ( a16 )            // 15001
         ? Scan ( a16, 1 )          // Returns 15001 too