1. A method for mapping a first plurality of source columns from a source file to a target file, each column of the source file having a header and a plurality of cells, each cell containing content, the target file having a second plurality of target columns, at least some of the target columns modeled to represent a third plurality of predefined entities, comprising, for each source column: evaluating heuristically whether the header for the source column matches at least one of the predefined entities, and if so, creating an initial mapping of the correspondence between the source column and the predefined entities; evaluating probabilistically whether the cell contents of the source column correspond to at least one of the predefined entities, and if so, creating an initial mapping of the correspondence between the source column and the predefined entities; assigning an entity score to the likelihood that the column corresponds to the predefined entities in the initial mapping; for each predefined entity, comparing the entity score to a threshold, wherein if the threshold is met or exceeded, then creating a final mapping of the correspondence between the source column and the predefined entities, and wherein if the threshold is not met, then creating a final mapping of the correspondence between the source column and undefined entities; and transforming each source column to a target column in accord with the final mapping.