Tkachuk, Nikolay V.Kuklenko, Dmitry V.Ovasapov, Sergey V.Shchekotykhin, Konstantin M.Godlevsky, MikhailMayr, Heinrich C.2020-01-072020-01-07200113-88579-331-8https://dl.gi.de/handle/20.500.12116/30733Some modern trends in software maintenance domain are depicted and discussed. The case study related topics, solutions, as well as some challenges and open problems based on the real maintenance project’s experience in the Ukrainian gas-transport industry, are presented. The idea of knowledge-based unified Maintenance Environment for large legacy information systems creation necessity and possibilities is introduced and discussed, and its first knowledge model specification is presented.enText/Conference Paper1617-5468