There are only a couple of definitions that apply here. These are commonsense definitions that will help to understand this chapter.
A value rule is the computation of one or more values from real data. It can mean anything that is computed from either selection of data values, summaries of values, or computations over the values. The results can be put in a file, on a report, in a spreadsheet, or anywhere that facilitates review. They can also be recorded in the data profiling repository for a permanent record of results.
This is the process of reviewing the results of a value test to determine whether the result matches your expectations. Because value tests are not hard-rule tests, the expectations will be very broad in nature. You are looking for surprises.