1. method for classification, the method comprising: identifying, by the computer system, in one or more import records a plurality of attribute-value pairs each having an attribute label not found in a native schema and a value; identifying, by the computer system, one or more attribute labels in the native schema having as possible values one or more values corresponding to the values of the plurality of attribute-value pairs; and generating, by the computer system, one or more normalization rules relating one or more attribute labels of the plurality of attribute-value pairs to at least a portion of the one or more attribute labels in the native schema.