1. A method for mapping fields of an input document structured according to a first format, the method comprising: identifying a plurality of first fields in the input document, wherein each first field includes a descriptor and text content associated with the descriptor; and for each first field: evaluating, via one or more natural language processing techniques, semantic properties of the descriptor and the text content against a plurality of mapping rules to determine whether the first field is consistent with one of a plurality of second fields in a target format, wherein each mapping rule specifies characteristics associated with one of the second fields in the target format, and upon determining that the first field is consistent with one of the second fields, defining a mapping from the first field to the second field determined to be consistent with the first field.