14. The method of claim 1 , wherein the structural elements defined in the grammar comprise iterating static structural elements each of which appears in all of the electronic messages in the respective cluster and repeats in a plurality of the electronic messages in the respective cluster.
14. The method of claim 1 , wherein the structural elements defined in the grammar comprise iterating static structural elements each of which appears in all of the electronic messages in the respective cluster and repeats in a plurality of the electronic messages in the respective cluster. 15. The method of claim 14 , wherein: the parsing comprises ascertaining as iterator related field tokens the field tokens that are associated with the identified tokens that correspond to the iterating static structural elements defined in the grammar; the determining comprises choosing as iterator classification features the identified tokens corresponding to iterating static structural elements adjacent the field tokens ascertained as iterator related field tokens; and the classifying comprises labeling the field tokens ascertained as iterator related field tokens based on the respective iterator classification features.