Ahh, OK, I now understand. adm_set is a temporary variable used by the previous declaration.  But now that I have looked at this more closely, I am confused.

-- The first rule says "if there's a P link and an RS link, then do something, and set adm_set to a value"

-- The second rule says "If there's an RS link, and adm_set is not set, then do EXACTLY the same thing as the first rule"

So why do we need the first rule?