Sorry, missed this one.
> If we have, for example, three characteristics each with two partitions each - when > generating test cases do we have to include each characteristic within the test? Or > can we have tests which just incorporate "subsets" of the characteristics. Thanks!
This is the whole point of coverage criteria.
What tests you'll have to generate depends on what criteria you are using.
If you used "all combinations", for instance, then you'd write tests for every possible
partition of a characteristic with those for every other characteristic (except for those
that are infeasible: for instance, if testing a string containing words, you can't have a
string that is both "empty", and "contains 2 or more words").
If you use other criteria, you'll need fewer tests.