Attributes in elements closing tag?

Question

Is it considered valid to do the following:

<li>stuff</li class="randomlengthclassname">
<li>stuff</li class="shortclassname">
<li>stuff</li class="reallyreallylongarseclassname">

or do the attribute have to be in the opening tag?

Answer 1

No it isn't. You must use attributes in the opening tag.

Running <a>test</a href="tst.html"> in w3c validator results in this error:

name start character invalid: only S separators and TAGC allowed here

Where S separators and TAGC are:

    S is "whitespace" separator

    [5] s =

        SPACE | (32) space
        RE | (13) CR
        RS | (10) LF
        SEPCHAR (9) HT

            -- http://xml.coverpages.org/sgmlsyn/sgmlsyn.htm#C6.2.1

    TAGC    ">"

            -- http://www.w3.org/TR/sgml.l

Answer 2

This is not valid, and all attributes must be defined in the opening tag, indeed.