This partitioning must be unidirectional in the case of an installation of class 1 from the
industrial system to any other network, including another industrial network of the same
company or institution, whether of lower class or of the same class.
CLASS 1: Companies which consist of only one department
with a single programmable installation or which have several departments with such
installations which are interconnected and for which this installation or these
installations constitute(s) the main activity.
This partitioning must also be unidirectional in the case of an
installation of class 2 from the industrial system to a public network or to another
industrial network of class 3.
CLASS 2: Companies which comprise more than one
department and whose connected and/or programmable installations are not interconnected with
each other but for which such facilities constitute the principal activity.