Different words, phrases, things like that can be spotted by a good adviser...a profiler perhaps...
You can bet that President Trump and his people have a clear idea of who it is and how it is being done, none of which we know, and we will find out about after it happens...
And do we know for sure the story of the people that didn't pass the test to get Security Clearance wasn't some people who the Administration fired and hasn't been brought out yet??? No, we don't, yet another story is it ‘very fake news’ also???
Change the number each time, give it to various people, see the number referred to in the leak, bingo, you have the leaker.
100,000 is the AP/Schumer magic number.