HTML incorrect specification?

Hi all,
Just a minor potential bug, on behalf of a friend of mine who is an author
who was asked to use your tool in preparation for online publishing.

He was having trouble using epubcheck, due to its current lack of front end
and his lack of technical knowledge, so I helped him out by installing the
tool myself and running his first book through it. It came up with three
errors, which when I dug down, all indicated that one particular HTML file
within the epub was using an attribute tag incorrectly, but as far as I can
see, it's not.

Specifically, this chapter of the book contains an ordered list, with items
1 to 9. Inside item 6, there is another ordered list, with items 'a'
through to 'd'. However that list is in turn broken up by a series of
quotes, which means that the HTML parser has broken that second list into
two; the first has one item, named 'a', and the second list (after the set
of quotes) has three items, defined with the value attribute of '2', which
parses correctly as 'b' through to 'd'.
The only restriction I can see is that this value attribute can only apply
to ordered lists, not unordered lists, which makes sense.
However the epubcheck tool appears to think that the value attribute can't
apply to any list object,
Without downloading the source code, and an environment editor, and then
trying to find the exact line that creates this error, I can't confirm
whether this is a bug or not. But it seems like it.

Meanwhile, I've explained to my friend what's happening and he's decided
that it's easier for him to modify the list formatting in that page of the
book rather than get involved in the technical aspects here.

Please let me know if someone can confirm that this was a bug, I'm curious
and hopeful that this email is useful to you.

Thanks for your time and effort!
Jeremy.