XMI21 — XMI 2.0 terminology

I am reading through the XMI 2.0 "convenience document" ptc/04-06-11 and
I am getting stuck trying to figure out the terminlogy. In particular,
what precicely is a "reference," what is an "association end," and what
is an "association role?" "Reference" and "association end" seem to be
leftovers from MOF 1.4, while "association role" is maybe a leftover
from UML 1.x. But, as far as I can tell these constructs do not exist
any more in MOF 2, so some definitions for them are need. Are these
suitable definitions?:

Reference: A reference is a Property owned by a Class (ownedProperty)
with isComposite=false and a type that is a subtype of Class.
Association End: An association end is a Property owned by an
Association (ownedEnd).
Association Role: An association role is an association end.

In section 7.8.4, there is a statement "For multi-valued Properties, no
XML attributes are declared; each value is encoded as an XML element."
However, the OMG-provided XMI 2.0 representations of the EMOF/CMOF
models use attributes to represent multi-valued Properties that meet the
definition of "Reference" above. This seems to be a contradiction. I
assume that the XMI spec should say "For multi-valued Properties, no XML
attributes are declared; each value is encoded as an XML element, unless
the Property is a Reference."