Red symbols correspond to values observed during absolute measurement sessions.

Two types of Adopted Baselines have been introduced: approved one, calculated till the end of the preceding year from observed baseline values using spline smoothing (green marks), and current one, re-calculated from 1 December of the preceding year each time new absolute measurements are obtained (blue marks).

Discontinuities in baselines are defined using information on extraordinary technogenic events taking place at observatories, provided by observatory operators.