Face1/Face2 angles can be collected in any order. The only requirement is that the Face1 backsight be recorded first. If Face2 observations are recorded, then a corresponding Face2 backsight should also be recorded. In the case where Face2 foresight observations are recorded previous to the Face2 backsight, the Face2 backsight is assumed to be the Face1 backsight plus 180°.
AutoCAD Civil 3D uses all reciprocal observations to a point (both foresight and backsight) by calculating an average horizontal and vertical distance of all the observations as long as the distance is a non-zero value to calculate the average horizontal and vertical position of a point.
The correct average for all Face1/Face2 and reciprocal observations is applied when the [adjust] command is used. An adjustment may be done to get the correct average values whether there is a closed traverse or not.