User-Defined Fields are key building blocks for customization. They are easy to create, available across the system, and provide great level of flexibility that enables the business to gain the most of SAP Business One. No wonder UDFs are widely used, and as such every enhancement in their capabilities means more customization options and more solutions. One of the powerful capabilities of UDFs is the feature enabling to link the UDF to another object. To support additional use cases and increase customization accuracy and efficiency, additional objects are added to the list (please see the image on the right):
Locations (OLCT), States (OCST), Units of Measurement (OUOM), Payment Terms (OCTG), and Resources (ORSC) are available in the “Link to System Object” list when choosing the “Linked to Entities” validation type.
Available in SAP Business One 10.0 FP 2105 and SAP Business One 10.0 FP 2105, version for SAP HANA.
Source: SAP community