Constraint rules are a variation of calculation rules. Constraint rules don't specify any ''expected'' value, because they have an implied expected value of true (or false).

For example, the following constraint rule table is checking the constraint that the ''a'' value is less than the ''b'' value. It only has ''given'' columns:

|!-fitlibrary.eg.Constraints-!|

|''constraint''|
|''a''|''b''|
|1|2|
|2|5|

The two rows are colored green because the constraint is satisfied. For each value row, the method ''aB()'' is called in the class ''!-Constraints-!'' below. If the method returns ''true'' the row passes, otherwise it is colored red.

In general, it's useful to show passing and failing constraint rules. Here we show some numbers that fail to meet out constraint (> 0):

|''constraint''|
|positive|
|1|
|435|

|''failing constraint''|
|positive|
|0|
|-3|
Here's the ^ProgramCode