HP 54710A User's Reference Manual page 209

Measurements
Measuring time intervals
The HP 54720 allows you to select time/division settings other than the
standard 1-2-5 sequence. For example, consider a pulse that is 5.8 µs wide.
At 1 s/division, the pulse will be 5.8 divisions wide, or 58 percent of the
screen width. However, at 500 ns/div, the leading and trailing edges will not
be on the screen simultaneously. Here, you could set the time base to
650 ns/division, and the pulse will occupy 90 percent of the screen.
Selecting the maximum memory depth optimizes the resolution of the pulse
width measurement, at the expense of throughput. Select the Acquisition
menu and set the memory to the maximum (16384 points for single-width
plug-ins). The double-width plug-in, HP 54721A, gives you twice the memory
depth because it uses two of the mainframe's digitizing channels and
associated memory. Therefore, in some situations it is better to use the HP
54721A plug-in for increased memory, though you may not need the higher
sampling rate it provides.
The HP 54720 has automatic measurements for all common pulse
parameters. You can configure the Delay automatic measurement to
measure any arbitrary time interval. Use the Define Meas menu to specify
which interval the Delay automatic measurement will measure. You can store
several custom delay measurement configurations using the Setup Storage
menu
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