The National Institute of Standards and Technology (NIST) provides a measurement service, number 65200S, "Fast Repetitive Pulse Transition Parameters, " for measuring the impulse response of high-speed (transition durations > 7 ps) samplers and the output signals of high-speed pulse generators. The 65200S provides traceable measurements of the waveform parameters of waveform amplitude and transition duration (also known as rise time or fall time). This measurement service has recently been improved using new measurement instruments and procedures, more accurate estimates for the behavioral characteristics of the test instruments, and an improved uncertainty analysis. The improvements to the 65200S include reduced transition duration uncertainties (about 1.5 ps) and the introduction of the parameters of overshoot and undershoot.