This relates to test case setToUntyped-010.xq

The essence of this query is:

copy $var1 := document { <test oldattr="abc"><content/></test> }
modify replace node $var1/test[1]/@oldattr with $input-context/BOOKLIST[1]/BOOKS[1]/ITEM[1]/@CAT
return
    (
    $var1/test[1]/@CAT instance of attribute(*, xs:untypedAtomic),
    $var1/test[1]/@CAT instance of attribute(*, xs:string)
    )

and the expected result is that @CAT is typed as xs:string.

I think this is consistent with the rules for upd:replaceNode() as written in 3.1.8. However, it creates an inconsistent data model. The rules for the copy-modify expression (2.4.5 clause 1.c.i) ensure that the test attribute is xs:untyped, and XDM consistency requires that the attributes of an xs:untyped element are all xs:untypedAtomic.

I believe that clause 1.b of 3.1.8 should change from

"If the type-name property of parent($target) is xs:untyped, then upd:setToUntyped() is invoked on each element node in $replacement."

to

"If the type-name property of parent($target) is xs:untyped, then upd:setToUntyped() is invoked on each element and attribute node in $replacement."

and the result of this test should then change so that @CAT is xs:untypedAtomic.