HP 8712ES User Manual page 149

Figure 4-8
Figure 4-9
Peak and Minimum Search Criteria
When the maximum or minimum point is at or near either edge of the
display, the excursion requirement is satisfied by a half of a division
excursion on just one side of the maximum (or minimum). See
Figure 4-9.
Peak and Minimum Search Criteria at Display Endpoints
ES User's Guide
Using Instrument Functions
Using Markers
4-15