Completion of the CLC1990 data layer in the context of the eponymous project (produced under the European Commission) took 10 years (Feranec et al., 2012), the longest time compared to the three CLC data layers that followed. The time range of the interpreted images even covered 12 years (1986-1998) (Feranec et al., 2012). This fact should be borne in mind especially when comparing the results of land cover (LC) change analysis from different parts of Europe for the period 1990-2000. The progressive inclusion of the partner European Union (EU) countries from Central and Eastern Europe into the project after 1993 had significantly influenced the completion of the CLC1990 data layer.