During a project to make our XML content WCAG-compliant, we discovered some older topics that have faulty table tagging structures in them -- multiple <tgroup> nested within <table> -- the structures are legal per the DTD, but are not compliant with Suitehelp 5 and WCAG accessibility readers. To efficiently update that content, we needed to search the repository for topics that contained this tagging structure: <table><tgroup>…</tgroup><tgroup>…</tgroup></table>.
After logging a support ticket, we were told that Tridion Docs cannot search structured content for multiple tags on multiple levels of a tagging structure. Searching for a single tag (<tgroup>) or multiple tags (</tgroup><trgoup>) on the same level of the tagging structure returned thousands of unfiltered or inaccurate results.
A CMS that manages structured content should be able to search the tagging structure of that content effectively, down to at least two levels.