Compound step terminology (editorial)

Just an editorial point:

I find the description of compound steps in 2.1 rather unclear.  What
are the contained steps of a p:choose?  Are p:when and p:otherwise
steps, or just syntax?  If the former, then 2.1 implies that they form
a subpipeline, when in fact each of them is a subpipeline.  If the
latter, then p:choose doesn't have any contained steps, because the
steps don't "occur directly" within p:choose.

-- Richard