A dictionary is a reference table that contains the substitute data and a serial number for each row in the table. Create a reference table for substitution masking from a flat file or relational table that you import into the Model repository. Business Case: The requirement here is to be able to match records from the source against a lookup table based on the a descriptive field and then obtain related attributes from the best possible match in the lookup table.For example, the source field ?PETER D THOMPSON? may exist as ?THOMPSON PETER D.? in the lookup table. To the human eye these records are a match. However, this type of lookup cannot be performed using a regular PowerCenter Lookup transformation. The requirement is to be able to ?fuzzy? match against the lookup table and establish that these records satisfy the ?lookup? condition.The attached document and mapping sample describes the challenge and the solution in detail.