Typo?

  Hi

  I've just noticed that the step pfx:atomic-step appears
twice exactly the same in the §D Pipeline Language Summary.
I guess this is because this step is defined twice in both
sections §4.7 Atomic Steps and §4.8 Extension Steps?

  By the way, I didn't see any explanation about the prefix
pfx:, and I find its uses quite confusing in the draft of
the 1st of May.

  Hope that helps.  Regards,

--drkm