A serial number is a unique identifier assigned to a software product or a device to identify it and prevent unauthorized use. In the context of Digsi 4.94, a serial number is required to activate the software and access its full features.

Digsi 4.94 is a software tool used for configuring and parameterizing protection devices, such as relays and controllers, in power systems. The software is widely used in the electrical power industry for ensuring the reliable and efficient operation of power grids.