Viewpoint For Projects uses NBS classifications, but you can also add your own.

By default, the classification field functionality is not enabled. To enable classification fields, contact the Support team. You must have administrative rights within the enterprise to request this functionality.

Import your classification schema from an existing spreadsheet. Once added, you can manage them and enable them at the enterprise, site, and project levels.

Enable the classifications so they can be assigned to other levels by toggling the option. Select the I icon to see where the selected classification schema is enabled. At the site or project level, you can decide if you want to inherit the classifications from the level above or break the inheritance.