The EVRS is realized by a certain adjustment of the United European Leveling Network (UELN).
The data handling and adjustment are carried out at the UELN data and computing centre at the Bundesamt für Kartographie und Geodäsie (BKG) in Leipzig.
Starting point of the UELN95 project were the data of UELN73 (Ehrnsperger and Kok, 1986).
This initial network was step by step enlarged by:
- Substitution of data material of such network blocks which were already part of UELN73 but show current new measurements with improved (mostly more dense) network configuration (intensive enlargement)
Adding new national network blocks of Central and Eastern Europe which were not part of UELN73 (extensive enlargement)
The adjustment in geopotential numbers was performed as constraint-free adjustment linked to the reference point of UELN73 (tide gauge Amsterdam). For the UELN adjustment the program system HOENA developed at BKG was used.
In January 1999 the adjustment version UELN95/13 was handed over to the participating countries as the UELN95/98 solution (see Figure). In addition to the data a report by the UELN data centre, which describes the method of adjustment and the calculation of normal heights, was handed over to each participating country. One year later, after the EUREF symposium in Tromsø, this solution got the name EVRF2000.
The parameter of the adjustment were the following:
|Number of datum points
|Number of unknowns
|Number of measurements
|Number of condition equations
|Degrees of freedom
|A-posteriori standard deviation referred to 1 km leveling distance in kgal·mm
|Mean value of the standard deviation of the adjusted geopotential numbers (heights) in kgal·mm