1. A method comprising: receiving data, wherein the data is organized as a plurality of named fields and as two or more sets of values associated with the named fields, wherein each named field is assigned to a category; determining, for each category, whether there is at least one identifier field for that category, wherein each identifier field is a named field that acts as an identifier for that category; identifying, for each category, identifier fields, if any, for that category that have a unique value in the identifier field for that category for each set of values; and selecting one of the categories as a concept representing the sets of values.