The DOI importer can create invalid MODS if the DOI record contains HTML formatting elements.
Example DOI identifiers:
Creates <mods><titleInfo><title> containing <sup> element.
Creates <mods><titleInfo><title> containing <scp> and <i> elements.
For both examples, a MODS edit brings up a form with missing titles.
We were able to manually correct MODS by replacing < and > characters with HTML entities for each formatting element.