The value for these is weird.  Basically, the only time it matters is if it's $log.EXCEPTION, in which case the meta-data tells us to try and interpret what we receive as an exception.  The rest of the time, my convention is that 'true' means that the value is somewhat we would have our test generate expectations against, and 'false' means that the value would not have expectations against it.  In this case, it's test meta-data, so you can't even write an expectation against it.  I know it's weird :(  Something to fix in the refactor!