Symantec Service Desk 7.5 - Classifying an incident only for SubCategory alone

Hi,

I am setting up service desk 7.5 in my environment.
My question is how to select only SubCategory to for specific classification without inherit the rule to
Main Category.When i add condition for example: Classification -Is Specific Classification -"Hardware.Notebook.Fax".
When i apply this the rule, all the category along the path inherit the rule as well.
I have several sub category having Fax in the list,so i dont think can use keyword to define it specificly.
I m really stuck at this point need help badly.

 

Thanks