xmllint.exe --xpath " //header[ contains(.,'rationale') ]/child::text() | //header[ contains(.,'rationale') ] /l/preceding-sibling::*   " fudge


                   1. Purpose and rationale
                   <p>purpose 1</p>
                   <p>Purpose 2</p>
                   <p>purpose 3</p>


                    2. Purpose and rationale
                    <p>2 purpose 1</p>
                    <p>2 Purpose 2</p>
                    <p>2 purpose 3</p>