Question on metadataExportMode for web engine

Hi, This is my first post. I'm working on creating a web gallery plugin.
I noticed there is a feature 'Metadata' with options 'All' or 'Copyright only' in default HTML gallery 'Output Settings' for exporting metadata to generated slide images.

I can see the code behind in galleryInfo.lrweb in the template folder how it's included.
My question is, what is the equivalent coding required to include this feature if I'm using galleryMaker.xml format?
Tried different combinations but none work.

<metadataexportmode>all

Is that correct? How to write the interface coding?

<metadatamodecontrol>


?

Thanks