The S/N labels for D22 fixtures are located behind the yoke adjustment knob on the right side of the fixture, as shown below:
User Interface
While the serial number label will in most cases be the quickest way to find the serial number, it may be difficult to access or read in field conditions. In this case, on fixtures which have a user interface, you can find the serial number in the Advanced Settings -> Diagnostics -> About Fixture menu, as shown below:
In Fos/4 products and Source 4 LED series 3, the menu structure differs — Diagnostics is a top-level menu option.