Test 6.1.3.b xsi:nil

Dear Forms WG -- I have the action to rewrite test 6.1.3.b which is
concerned with the behavior of xsi:nil in the Required MIP.  The definition
of Required is as follows:

A form may require certain values, and this requirement may be dynamic.
When evaluating to true, this model item property indicates that a
non-empty instance data node is required before a submission of instance
data can occur. Non-empty is defined as:

   1. If the bound instance data node is an element, the element must not
have the xsi:nil attribute set to true.
   2. The value of the bound instance data node must be convertible to an
XPath string with a length greater than zero.

According to W3C schema: An element with  xsi:nil="true" may not have any
element content but it may still carry attributes.

So it does not seem possible to test the behavior of xsi:nil strictly on
the presence of element content...there is no valid case where
xsi:nil="true" can also appear with non-zero length instance data.  Hence
the two conditions above would seem to be redundant.

Perhaps I've missed something in the last couple of discussions on this
point...my recollection is that we wanted to rework the test solely to
examine the presence of xsi:nil="true" and suppress submission regardless
of element content.  We can write the test this way, but that instance
would fail schema validation anyway given the element content...I don't
suggest we do this but is that what was intended???

Thanks, Charlie Wiecha