1cdf8355_s_of_a_Faceted_Navigation_OPAC__Logical_Rule
[Coded Action] Facet Search [Explanation] Refines the result set by selecting a facet [Logical Rule] 
N has a value other than “0”. N value is different from previous N value, or N has an additional value that was not present in the previous N value. If multiple values have changed, takes precedence over all but a change in Ntt value.
The Code4Lib Journal – Extracting User Interaction Information from the Transaction Logs of a Faceted Navigation OPAC