How to parse embedded extended tags

Thanks to the folks in this forum – whose names I can't recall, except for Florian and ohrenkino – I have happily exported tags into CVS files. However, I've recently hit a snag that I am unable to handle: several tags that are embedded in a tag. I am cataloging my audiobooks and some of them have time markers that I want to identify, e.g.:

LENGTH 000003897457
OVERDRIVE MEDIAMARKERS Markers><Marker><Name>Opening</Name><Time>0:00.000</Time></Marker><Mark
PUBLISHER Hachette Audio

My latest attempt to parse:

$filename(csv,utf-16)Filename$char(9)
$loop(%_filename_ext%)%_filename_ext%$char(9)%overdrive mediamarkers%$char(9)%Markers%$loop(%Markers%)%Marker% %Name%$char(9)%Time%$char(9),$loopend(),$loopend()
build on %_date%

The output:
Filename

Part 01.mp3	<Markers><Marker><Name>Opening</Name><Time>0:00.000</Time></Marker><Marker><Name>Chapter 1</Name><Time>0:45.000</Time></Marker><Marker><Name>Chapter 2</Name><Time>6:25.000</Time></Marker><Marker><Name>Chapter 3</Name><Time>15:24.000</Time></Marker><Marker><Name>Chapter 4</Name><Ti …
build on 4/29/2024

A tutorial on how to script for these items (and the proper name for what I think of as "embedded tags" would be greatly appreciated!

I think that OVERDRIVE MEDIAMARKERS is a user-defined field that should be left as it is.

So far I am not really sure what you want to achieve. Do you want to transform the XML-tags into ID3 tags?