Multi-parts
When a manuscript contains multiple A-Z or essay parts group each set of parts by wrapping each set of parts within a parent part element.
//part/part
This should only be done if there are multiple A-Z or essay sections.
No role attribute value is needed.
<mainText>
<part><part role="essay"> </part><part role="A"> </part><part role="B"> </part><part role="C"> </part>
</part>
<part><part role="essay"> </part><part role="A"> </part><part role="B"> </part><part role="C"> </part>
</part>
</mainText>