A system and method for mapping columns from a source file to a target file. The header for each source column is evaluated heuristically to see if the header matches a predefined entity. The contents of a group of cells in the source column are evaluated probabilistically to determine a probability that the cell contents correspond to at least one of the predefined entities. A score is assigned to the likelihood that the column corresponds to one or more predefined entities. If the score meets a threshold, then the correspondence between the source column and one or more predefined entities is mapped. If the score fails to meets the threshold, then the correspondence between the source column and one or more undefined entities is mapped. Finally, each source column is transformed into a target column in accord with the map.