gin is still needed to be confirmed. For any structure, the degree of confidence in the impact origin is reflected by its validity index V , that can adopt the following values: 4 (confirmed), 3 (probable), 2 (possible), 1 (suspected) and 0 (rejected). The latter relates to the structures, whose once proposed impact origin was later disproved by additional studies. Classification of structures over the validity index is based on some sort of expert judgment and reflects the availability of

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... t criteria found at four different levels: morphological, geological, petrological and mineralogical. Currently, the database contains 1082 structures, among them 206 structures with V = 4, 186 structures with V = 3, 501 structures with V = 2 and 75 structures with V = 1. In addition to the main parametric table, the database in its current version contains over 3200 photos and maps, 860 textual descriptions and 1145 bibliographical references.