Elgin,

Yes, they're logically equivalent.

>Sergey,
>
>Thank you again. I tried out both your examples. I'm sticking with the second one. I'm assuming the only difference between your two examples is readability, correct?
>
>>Elgin,
>>
>>It should be

     IF  !("PCB" $ UPPER(fluid)) ;
>>        AND !("PYRANOL" $ UPPER(fluid)) ;
>>        AND !("WECOSOL" $ UPPER(fluid))
>>* OR
>>     IF  NOT ( ("PCB" $ UPPER(fluid)) ;
>>        OR ("PYRANOL" $ UPPER(fluid)) ;
>>        OR ("WECOSOL" $ UPPER(fluid)))
>>