Malan is a MApping LANguage that allows the generation of transformation programs by specifying a schema mapping between a source and target data schema. By working at the schema level, Malan remains independent of any transformation process; it also naturally guarantees the correctness of the transformation target relative to its schema. Moreover, by expressing schemas as UML class diagrams, Malan schema mappings can be written on top of UML modellers. This paper describes the overall approach by focusing on the Malan language itself, and its use within a transformation process. Categories and Subject Descriptors I.7 [Document and text Processing]: Document Preparation--Markup languages; E.0 [Data]: General General Terms Design, languages Keywords mapping, Malan, UML, data manipulation, schema transformation, schema translation