Spectra Precision Survey Pro v4.5 Recon and Nomad Reference Manual - Manual (Page 253)

Survey Menu – Basic GPS Module
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an existing point name when the base is set on an existing job point.
GPS Backsight/Resection
GPS Backsight GPS Resection
The GPS Backsight/Resection screen will open any time the
coordinate system is not solved. It will have one of two states
depending on if the base was set up on an existing job point and one
additional control point is needed to orient the setup, or the base was
set up on a new point from an autonomous setup.
Occupy Control > : opens the Occupy Control Setup screen, described
below.
Use base as vertical benchmark : Check this box if the base is set up
on a job point with an accurate elevation to include it for vertical
control during localization.
Start Now : opens the Data Collection screen without collecting GPS
control at this time.