quoted strings without word= prefix inside a div tag cause the div to be output as text

[epo001]

A web page contained something like this

<div style="font:foo;" "odd:stuff">actual text</div>

despite either of :fixup_tags and :xhtml_restrict my script presented the following as text

<div style="font:foo;" "odd:stuff">actual text

and the div was not recognised as such, if I deleted the "odd:stuff" then it behaved as expected, i,e, returning actual text as the text.