Either way, the trailing slash will probably be at least optional.

At most optional. The slash being treated as optional is the best possible result, not the worst. The possible outcomes range from "incorrectly used and ignored" to "incorrectly used and gives an error". (Browsers don't support the correct use.) The OP's browser is apparently somewhere in the middle of that range since it ignores the error for rendering purposes while discretely notifying the user of the error ("red circle with an X in it").

especially with a doctype of 4.0 transitional that tells us to expect a jumble of tag soup

It sounds like you're saying transitional documents don't have to be well-formed, and that's not true.

In reply to Re^2: For valid HTML by ikegami
in thread For valid HTML by Lady_Aleena

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