Level 4 is home to all the Information Technology (IT) systems that support the production process in a plant of a facility. These systems report production statistics such as uptime and units produced for corporate systems and take orders and business data from the corporate systems to be distributed among the Operation Technology (OT) or ICS systems.
Systems typically found in level 4 include database servers, application servers (web, report, MES), file servers, email clients, supervisor desktops, and so on.