====== What is a compplex sensor? ======

If you have configured at least two simple sensors, you can combine them by creating a compound sensor. Creating compound sensors is described by logical expressions like:

   * ' ( 4 and ( 3 or ( 1 and 2) ) or 2 '
   * '1 and (3 or 2)'.
   * '1 and 2'.

Note that to write the expression correctly ** all characters must be separated by spaces **.