Strength stripper functions

In this case, the test for A=B would not result in a type mismatch but B can still be X or Z - states that A cannot possess. To prevent this ambiguity occurring, strength stripper functions can be called to convert such excess states to allowed states. See Box 7.1 for more details of these functions and where they can be used. 

The object types in the output assignment statements have been mixed. This has been done purposely in this case to demonstrate the use of the conversion function TO XOIZ with the signal CMP. Conversion and the similar strength stripper functions were discussed in Chapter 7. 

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