identify the baseline/be baseline node in identify the reference/be the reference node in defined for/utilize identify the observing/be observing facility in be a property of/have a property of be a property of/have a property of be a property of/have a property of be a property of/have a property of be part of/be assembly of facility reference point observation definition position sensor facility positioning measurement activity pty azimuth pty length pty plane angle pty sensor calibration pty transient property well surface point earth surface point