User Data fields are provided in the Property Editor as a resource for users to provide additional data, or better described as the purpose of the data. Each object is provided up to eight "User Data" property fields that may be used for filtering into a "Smart Folder", displayed in the Sheets view, and displayed in the Network view.
Each of these eight "User Data" property fields can also be relabeled with user defined titles per object type. Reference User Data Tags for information to customize the User Data properties per object type.