w3 manual does not permit modification?

The texinfo manual for w3 has the following license notice:

    Permission is granted to make and distribute verbatim copies of
    this manual provided the copyright notice and this permission notice
    are preserved on all copies.

    Permission is granted to process this file through Tex and print the
    results, provided the printed document carries copying permission
    notice identical to this one except for the removal of this paragraph
    (this paragraph not being relevant to the printed manual).

    Permission is granted to make and distribute verbatim copies of@*
    this manual provided the copyright notice and this permission notice@*
    are preserved on all copies.

This doesn't give any permission to modify the manual.  Is this
intentional?  Could you clarify the license?
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-- 
Ben Pfaff 
email: blp <at> cs.stanford.edu
web: http://benpfaff.org