A computer-implemented system and method for tagged data and rectangular data conversions. The system and method receive tagged input data that is in a non-rectangular format and uses a hierarchical arrangement of tags to indicate data relationships. Data directives are used to parse the tagged input data. The data directives indicate which tags in the hierarchical arrangement of tags are to form which columns in the rectangular formatted data output. The rectangular formatted data output is generated based upon the parsed tagged input data. The data directives may also be used to convert rectangular data into a tagged data format.