subtype - If S is a subtype of T then an expression of type S may be used anywhere that one of type T can and an implicit type conversion will be applied to convert it to type T.
In object oriented programming, this means that objects of type S must accept every message that one of type T would
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дс тдрлими цюлютдажкию дроемжки аиакиохдйис лидр
http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi;
