The external reliability is an indicator for coordinate reliability. The external reliability of a point describes the effect of an undetected gross error on the coordinate. In the network plan, the external reliability of a point is represented by a rectangle in which its coordinate is located with a probability of 99%. Otherwise the gross error would have been detected.
The reliability tolerance is specified in the field code list. Click the Manage Field Code List link to open the Manage Field Code List dialog box. Click the Distribution tab. See also Reliability Tolerance Statement.
Click the Analyze Length Reliability Rectangle link to display the Calculated Coordinates tab in the Result dialog box. Examine the values NA, NB, NH, and N Bearing.
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Green light indicates that the reliability of all points is within the tolerance. When you distribute the point, NA will be stored in the attribute TB_RELIABILITY_POSITION, and NH will be stored in TB_RELIABILITY_HEIGHT. -
Yellow light alerts you that for some points no reliability tolerance is specified, so that the analysis could not be completed. Or some of the single measurement points do not have over determination (NA = Infinite). -
Red light indicates that some points are not within the tolerance. The list displays the 5 points that have the largest NA values.
Reliability Rectangle
For each new point, the reliability rectangle describes the effect of an undetected gross error on the coordinate and on the height. The size and orientation of the rectangle are: NA (long side) NB (short side), and N Bearing (bearing of the long side).