Elbow; Color Codes - Universal Robots e-Series Original Instructions Manual

5. Safety Configuration

5.11.3. Elbow

You can enable Restrict Elbow to prevent robot elbow joint from passing through any of your
defined planes. Disable Restrict Elbow for elbow to pass through planes.

5.11.4. Color Codes

Gray
Plane is configured but disabled (A)
Software Manual 41 e-Series