Question on clear applying to run-ins

From: Boris Zbarsky <bzbarsky@MIT.EDU> Date: Fri, 15 Jan 2010 22:45:22 -0500 Message-ID: <4B513652.9020709@mit.edu> To: www-style list <www-style@w3.org> · This archive was generated by hypermail 2.3.1 : Monday, 2 May 2016 14:38:31 UTC

Section 9.5.2 says:

  For run-in boxes, this property applies to the final block box to
  which the run-in box belongs.

What does that mean exactly?  Is the block supposed to clear whatever 
the run-in would clear (in addition to whatever the block itself 
clears)?  Or is this just saying that the block is the right block 
formatting context for the run-in's clearance?  Or something else?

-Boris