It is well-known that data-snooping can only be interpreted when there are but 
small errors left in the network. Therefore gross errors should be eliminated 
before applying the data-snooping technique. Module KSCAN detects these gross 
errors with respect to observed directions. KSCAN runs fully automatical and 
searches for the smallest independent closed loops in the network. In these loops 
gross errors, if any, will be detected. For input the algorithm uses the topology of 
the network hence no coordinates or point identifications are to be entered by the 
user. 
After having completed KSCAN the blunders and gross errors will have been 
removed. GEOSCAN then executes module GSCAN. GSCAN is a graphics module 
which presents a color-graphics plot of the network on the screen. 
Pressing RETURN charges module ESCAN so that the three input files are 
converted into files needed for the least squares adjustment. In ESCAN the 
number of observations, number of unknowns and the number of redundancies are 
being calculated. 
4. IMPLEMENTATION OF THE DELFT APPROACH 
The least squares and statistical calculations are performed in module MSCAN. 
Therefore MSCAN includes the following main features. 
4.1. The design of a network 
There are three input files: 
- a file with approximate coordinates; 
- a file with network configuration; 
- a file with options. 
The computations are divided into: 
- 386 -