Add a new page where users can add technical metadata fields to be listed in the advanced search page by default.
This page should have an autocomplete text box to browse through the existing technical metadata field names.
The technical metadata definitions should be editable and deletable.
A technical metadata definition added in the promoted metadata fields page will appear in the default dropdown list on the advanced search page
The default dropdown list in the advanced search page will be grouped as User and Technical metadata definitions
Choosing one of the technical metadata definitions from the default dropdown list will search across the entire technical metadata where this definition appears mburnet2, please feel free to comment or edit the description.