7. The method of claim 1 , wherein, for each cluster, the structural elements defined in the respective grammar comprise static structural elements each of which appears in all of the electronic messages in the cluster.
7. The method of claim 1 , wherein, for each cluster, the structural elements defined in the respective grammar comprise static structural elements each of which appears in all of the electronic messages in the cluster. 8. The method of claim 7 , wherein: the parsing comprises ascertaining the field tokens that correspond to prices; the determining comprises choosing as price classification features the identified tokens corresponding to static structural elements that immediately precede the field tokens ascertained to correspond to prices; and the classifying comprises labeling the field tokens ascertained to correspond to prices based on the respective price classification features.