Agilent Technologies 1660A Series User Reference page 350

The Compare Menu
Specify Stop Measurement Field
X-O
The X-O option is available in the State analyzer with its count set to Time.
When X-O is selected, a repetitive run is stopped when a comparison of the
time period between the X and O markers and one of the following time
period options is true.
Less Than X-O time must be less than the time value that you specify
in the Time field.
Greater Than X-O time must be greater than the time value that you
specify in the Time field.
In Range X-O pattern must be within the time range value that you
specify in the two Time fields.
Not in Range X-O pattern must not be within the time range value that
you specify in the two Time fields.
X-O field
X-O Stop Measurement Type Fields
17–14
X-O options menu