[css21] clearance

In http://www.w3.org/TR/CSS21/visuren.html#flow-control it states "...  
then its clearance must be set to the greater of" and then "... to make  
the sum of the following equal ..." and the one of the following is "the  
clearance itself". This seems circular. What am I missing?


-- 
Anne van Kesteren
<http://annevankesteren.nl/>
<http://www.opera.com/>