K3 indicator
The K3 indicator was a measurement marker used by the 23rd century body function panel. This marker, not normally active, measured the level of pain experienced by a patient.

While treating Spock for a flying parasite infiltration in 2267, Doctor McCoy activated this indicator to illustrate to Captain Kirk how much pain the creature was inflicting. The indicator rose variably between 75% to 85% of its maximum; McCoy commented that it was "no wonder the poor devils go mad," implying that the pain indicated was severe. When Spock continued to speak, the indicator increased to nearly 100%. ()

de:K3-Messgerät
Medical equipment
Medical measurements