truewhen the attribute is not specified and has its default value, and
isntreverses the result.
attribute attribute-name (of element-expression)? (is | isnt) defaulted
is defaulted attribute type test succeeds when:
Otherwise, the test fails. Using
isnt instead of
is reverses the results.
Unlike most other attribute references, no error is generated if the specified attribute does not exist, or was not given a value, since the test does not actually use the value.
If the element-expression references an element that does not exist, or the specified attribute
is not declared, the
is form of the test always fails, and the
isnt form always