Starting in NX 6.0 we have introduced a new feature which will allow you to add what we call a 'Requirement' to an expression where you can define certain criteria to be used to check to see if you've entered the correct value or even if an expression which depends on other expressions has not fallen outside some desired range or not.
Some of the criteria which can be set are:
Single Sided Comparison
Where you can test whether an Expression value is Equal, Not Equal, Greater Than, Greater Than or Equal, Less Than, Less Than or Equal.
Double Sided Comparison
Where you can test is an Expression Greater Than, Greater Than or Equal to one value and also Less Than, Less Than or Equal to another value.
Set of Values
Where you can check the Expression value against a list of acceptable values.
Now this is not limited to only Floating Point Numbers, but also Integers, text Strings and Booleans (check for a True/False status).
Now there are 3 levels of 'severity' when failing a test, Error, Warning and Information. In each case the system will display a certain type of icon indicator in the expression Dialog showing that status of all Expressions with check requirements assigned to them. Expressions which pass their checks will have a 'Passed' indicator (Green Check-mark). Note that unless you arrange for some other action to be taken, setting up a check requirement will NOT prevent you from violating one or more of these check Requirements, but it will provide a scheme where you can quickly see where either entries or results are not conforming to your desired intent.
Note that these checks can also be assigned to measurement expressions which will allow you to flag measurements which you might have added to a model as a sort of geometric 'debugging' task.
Anyway, if you're using NX 6.0 you may wish to look into this. You can either create a Check Requirement on-the-fly from within the Expression editor (just select an existing Expression and press MB3 and you will see an option to 'Add a Check') or you can go to...
Analysis -> Check Requirements...
...and create or edit Check Requirements there as well as check their status and see how they are being used and what they are checking.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Cypress, CA
To an Engineer, the glass is twice as big as it needs to be.