Each across clue also describes how similar the across entry is to the five-letter meta answer. =that letter is not in the answer. =that letter is in the answer, but in a different place. =that letter is in the answer in the same place.
I just discovered this past week that Louis Sachar published a 4th book in his Wayside School Series (6th if you count the two Sideways Arithmetic books, which are also great). Wayside School is a 30 story tall building (if you count the 19th floor that does not exist), so the meta answer is twice that.