Engineering software group Aveva's shares fell back after it reported continued mixed trading across its geographical spread. The firm, which supplies 'Digital Information Hubs' to industrial plants, said it had seen strong performances in South Korea and South East Asia, but trading in North America "remains tough" and the performance in Europe is mixed "with Eastern and Central Europe performing satisfactorily whilst Southern Europe has remained challenging."Aveva said the oil and gas sector is continuing to perform strongly, while the power division continues to make steady progress and the marine division "remains robust." It said that it continues to invest in the "BRIC" countries, particularly Brazil and Russia."In order to better position ourselves for the significant opportunities that exist in China we have strengthened the management team and have undertaken a structural re-organisation to create a wholly owned subsidiary," it said. "As a result of these changes, we expect revenue to be more heavily weighted to the second half of the year in this region."