/*===============( Binary search at position )===============*/
BiSearchAtPos: Procedure Expose stem.
Arg search, atPos, len

If DataType( atPos ) <> 'NUM' Then atPos = 1
If DataType( len ) <> 'NUM' Then len = Length( search )
found  = 0       /* Index of the found Item */
bottom = 1
top    = stem.0

Do While found = 0 & top >= bottom
  mean = (bottom + top) % 2
  Parse Var stem.mean . (atPos) searchValue +(len) .
  If search = searchValue Then found = mean
  Else If search < searchValue Then top = mean - 1
  Else bottom = mean + 1
End

Return found
/*** End BiSearchAtPos ***/