Steps required:

1. Add a new custom attribute in the pop-up window by clicking All-Platforms->Global Settings->Manage Custom Attributes.

2. Set the required value for device/device-group in the Custom Attributes section of 'Devices details" tab in the Devices View. (It is possible to bulk import values for multiple devices with a CSV file by clicking the "View All Devices" options in latest MobiControl v14.2.1 web console UI).

3. Edit any desired "Columns View" to include your added custom attribute field(s)