How can I disallow certain combinations in my pricing calculator pricing engine?

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It is possible to disallow a combination of options in the pricing calculator pricing engines. If the user selects a disallowed combination, they will get a message that says, "That combination of choices is not allowed."  The method for setting this up will depend upon if you are using grid or pricing parameters.  

Grid Parameter:
In the grid, for the combination that should be disallowed, you would delete the contents of the pricing cell.  The disallowed combination in your spreadsheet would look like this:  
The result would look like this:  

Calculator Parameter:
You would need to use a custom "Applies To" (column E).  You would use an ifn statement.  See this example:  
In the example, the custom applies to is:
ifn(Paper=”Gloss”, Q1, -1)
This means that if the Paper option equals gloss, then the value is Q1, otherwise the value is -1.  If the user chooses Matte, then the value will be -1.  The calculator parameter has a minimum value of 1.  Therefore if the user chooses Matte paper and folding yes, then the value is disallowed.  The engine will return the " "That combination of choices is not allowed." message.