Question on section 2.7.1, Part 1

Dear Editors:
While attempting to put in some text on forwarding intermediaries in the Primer, I took a look at Section2.7.1, Part 1 [1],
and have a question about some aspects of the text there:

Para 2 says: "....They MUST also remove from the SOAP message all SOAP header blocks targeted at themselves, prior to forwarding, regardless of whether these header blocks were processed or ignored."

Para 3 says: "....Such rules MAY describe placement of inserted or reinserted SOAP header blocks. ...."

I wonder if the MAY in the last quoted part is valid for the case of a SOAP header block with a role attribute of "next". Surely for such blocks, the header block MUST be reinserted, whether this block is processed or ignored. In fact, shouldn't something be mandated regards forwarding for header blocks with a role="next"?

Please could someone clarify.
Thanks,
Nilo

[1] http://www.w3.org/2000/xp/Group/2/06/LC/soap12-part1.html#forwardinter