Agilent Technologies 1660A Series User Reference page 279

X and O entering / leaving Fields (Timing only)
If the analyzer is configured as Timing, the X and O pattern markers are
placed at either the beginning of the pattern occurrence (entering) or at the
end of the pattern occurrence (leaving). When the entering/leaving field of
either X or O markers is selected, it will toggle between the two choices.
Whichever choice you toggle the field to, the pattern you place in the pattern
display field will apply to that choice.
X-marker and O-marker Fields (State only)
If the analyzer is configured as State, X-marker and O-marker fields replace
the X and O entering/leaving fields. The pattern you place in the pattern
display field will apply to the marker labeled at the left.
X and O entering
and leaving fields
Specify Patterns Menu
The Waveform Menu
Specify Patterns Field
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