In many conference room display installations, the service tag label on the back of the monitor is not visible without dismounting the monitor.
Both the C5518 and C8618 displays have the service tag listed in the On-Screen display of the monitor.
Using the Touch Control launched then selecting the Menu button, Others, Service Tag to display the service tag, can provide the service tag information as long as the display screen is functional. (Figure 1.)
Figure 1. - Finding the Service tag on the on-screen display menu