[xacml-comment] Environment attributes

I'm unclear about the use of the time based context attributes, namely

Urn:oasis:names:tc:xacml:1.0:environment:current-time
Urn:oasis:names:tc:xacml:1.0:environment:current-date, and 
Urn:oasis:names:tc:xacml:1.0:environment:current-dateTime

Section 10.3.5 of the specification states that 'The value for these
attributes MUST be provided by the PDP', wheras  Appendix B8 states that
'When used, they SHALL appear within the <Resource> element of the
request context.'

Looking at tests AAA016-IIA021, it appears that the expected usage is
that the values may or may not be present in the request context, but if
they are not present then values must be supplied by the PDP. Also, when
values are being provided in the context requests of these tests, they
are appearing in the <Environment> element, not the <Resource> element.

Which, if any, of these is correct?

Cheers,
Tony