> Sorry, I don't understand what you mean by this.
I meant that the current test case would result in true in both
ordering - so in this sense, it's not the best testcase:
SELECT (istrue IMPLIES isnul) IS NULL FROM booltbl4;
SELECT istrue IMPLIES (isnul IS NULL) FROM booltbl4;
are both true
If you change it to
SELECT isfalse IMPLIES isnul IS NULL FROM booltbl4;
Then those would have different results, making it a better testcase.
