Agilent Technologies InfiniiVision 3000 X- Series Advanced Training Manual page 62

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Advanced Triggering, Search & Navigation, and Segmented Acquisition Labs
must remain stable ("hold" high or low) for a minimum amount of time
after the occurrence of the clocking signal before switching to the opposite
polarity. This is commonly referred to as the device's minimum specified
"hold" time.
Let's assume that data is being clocked into a device on the rising edge of
our clock signal (yellow trace). To determine the setup time of our signals
we could use the scope's timing cursors to measure the time from the
rising/falling edges of the data signal to the rising edge of the clock signal.
If you make this measurement based on the brighter green traces, then
you should measure a setup time in the range of 37 ns. But notice the
fainter green traces. It appears that our data signal is occasionally shifting
closer to the clock signal. If you make the setup time measurement based
on the fainter green traces you should measure a setup time in the range
of just 17 ns. Let's now assume that our device has a minimum specified
setup time of 25 ns. This would mean that the timing of our signals
usually meet specification, but sometimes they are in violation of the
specification. Rather than triggering on any rising edge of the clock
(current trigger condition), triggering on clock signals that are preceded by
a data setup time violation might help us to debug this timing problem.
Let's do it.
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Figure 42 Triggering the scope on just setup time violations of less than 25 ns.
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Press the [Trigger] front panel key.
Turn the Entry knob to select the Setup & Hold trigger type.
Press the < Setup softkey; then turn the Entry knob to set the minimum
setup time to 25 ns.
3000 X-Series Oscilloscopes Advanced Training Guide