15. The service center system of claim 14 , wherein the instructions to add include instructions to select the new salient term based on a word count indicative of a frequency with which terms occur in a selected set of user utterances.
15. The service center system of claim 14 , wherein the instructions to add include instructions to select the new salient term based on a word count indicative of a frequency with which terms occur in a selected set of user utterances. 16. The service center system of claim 15 , wherein the instructions to remove include instructions to remove the association of the salient term based on the word count.