[CSS21] WD 9.2.3: Spacing of run-in headings

  # If [A runs in to B] then A is rendered as an 'inline' element at the
  # start of B's principal box.
  # ...
  # ... example:
  #   ...
  #   <H3>A run-in heading.</H3>
  #   <P>And a paragraph of text that follows it.</P>
  #   ...
  # This example might be formatted as:
  #
  #   A run-in heading. And a ...

So <H3>A run-in heading.</H3> is rendered as an 'inline' element at the
start of the <P>.  But where does the space between ‘heading.’ and ‘And’
come from?

This appears to be either an underspecification (of what can be rendered
between the run-in and the body) or an error in the example.

pjrm.