line 10 column 1 - Error: <asset> is not recognized!
line 10 column 1 - Warning: discarding unexpected <asset>
line 11 column 1 - Error: <thumbnailimage> is not recognized!
line 11 column 1 - Warning: discarding unexpected <thumbnailimage>
line 9 column 1 - Warning: missing </div> before <caption>
line 12 column 1 - Warning: inserting implicit <table>
line 13 column 1 - Error: <width> is not recognized!
line 13 column 1 - Warning: discarding unexpected <width>
line 13 column 8 - Warning: plain text isn't allowed in <table> elements
line 12 column 1 - Info: <table> previously mentioned
line 13 column 10 - Warning: discarding unexpected </width>
line 14 column 1 - Error: <height> is not recognized!
line 14 column 1 - Warning: discarding unexpected <height>
line 14 column 9 - Warning: plain text isn't allowed in <table> elements
line 12 column 1 - Info: <table> previously mentioned
line 14 column 11 - Warning: discarding unexpected </height>
line 15 column 1 - Warning: discarding unexpected </thumbnailimage>
line 16 column 1 - Warning: discarding unexpected </asset>
line 17 column 1 - Warning: discarding unexpected </div>
line 12 column 1 - Warning: missing </table> before </body>
line 9 column 1 - Warning: missing </div>

Accessibility Checks:

line 1 column 1 - Access: [3.3.1.1]: use style sheets to control presentation.
line 4 column 1 - Access: [13.2.1.1]: Metadata missing.
line 12 column 1 - Access: [5.5.2.1]: <table> missing <caption>.
line 12 column 1 - Warning: trimming empty <caption>
line 12 column 1 - Warning: trimming empty <table>
Info: Doctype given is "-//W3C//DTD XHTML 1.0 Transitional//EN"
Info: Document content looks like XHTML 1.0 Strict
Tidy found 17 warnings and 4 errors!

This document has errors that must be fixed before
using HTML Tidy to generate a tidied up version.

For further advice on how to make your pages accessible
see https://www.w3.org/WAI/GL and https://www.html-tidy.org/accessibility/.
One or more empty elements were present in the source document but
dropped on output. If these elements are necessary or you don't want
this behavior, then consider setting the option "drop-empty-elements"
to no.

About HTML Tidy: https://github.com/htacg/tidy-html5
Bug reports and comments: https://github.com/htacg/tidy-html5/issues
Official mailing list: https://lists.w3.org/Archives/Public/public-htacg/
Latest HTML specification: https://html.spec.whatwg.org/multipage/
Validate your HTML documents: https://validator.w3.org/nu/
Lobby your company to join the W3C: https://www.w3.org/Consortium

Do you speak a language other than English, or a different variant of 
English? Consider helping us to localize HTML Tidy. For details please see 
https://github.com/htacg/tidy-html5/blob/master/README/LOCALIZE.md