1. Each experimental data point in Figures 1 and 2 is the average of three experiments in three identical model biles.

2. A virtual face and a datum point which embody basic semantics requirements are two low level objects.

3. The cause and rule of deformation of datum point are analysized by data of repetition. Finally, some useful conclusions and suggestions are also given.

4. This article introduces resection locating temporary work datum point by distances and angles in control network for deformation observation.

5. And secondary network lasts for 13 periods. Gravity datum is selected for datum network to analyse the stability of the datum point using mean spacing method.

6. It reviews the history and renovation process of the geodetic datum point in China and mainly describes the Kanmen zero point.