This parameter determines the maximum difference between numerical evaluations of the student response and question answers which will be allowed to count as matching. When the two expressions are evaluated and found to differ by more than the amount specified here then they will be regarded as different expressions. The value is treated as a fractional difference.
For example, if the student response evaluates to be 10.3 and the question answer evaluates to be 10.2 then the tolerance need only be greater than 0.01 [=(10.3-10.2)/10.2] for the expressions to be regarded as equal.