I believe there was previously a patch to fix this issue, but I can't find it, and anyway it might not be wise to reuse it.
If I upload an HTML galley file and label it as HTML in OJS Editor view, EDITING, at the Galley EDIT link, then click Save, OJS does not flip the switch in article_galleys.html_galley to 1, even though article_galleys.label is set to value "HTML". This does not seem to be a problem after the initial upload if after the initial upload I run a query in the database to update HTML labeled galley records, html_galley field, to 1 -- that is future uploads of the same galley file don't disturb the html_galley column value.
This means that when an HTML article is viewed, OJS does not generate/regenerate surrounding HTML markup, including DC metadata, etc.
This occurs whether the galley file is complete HTML (with an HTML opening and closing tag and no OJS-specific markup such as DIV#main or DIV#content) or partial HTML (using a pre-set article template that is meant to go inside the HTML BODY tag, and assumes that OJS will generate surrounding markup such as DIV#main, DIV#content, etc).
Thanks in advance for your assistance.