The IADAA position on "looted" antiquities

I have been rereading the IADAA (International Association of Dealers in Ancient Art) position on "looted" and "stolen" antiquities. Their statement is uncompromising:

IADAA also stands against the destruction of the past, whoever is responsible. ... IADAA will use every effort to raise awareness of such destruction. As our code of ethics makes clear, we refuse to deal in pieces, which are looted or stolen.

The code of ethics for the IADAA clearly states:

2. The members of IADAA undertake not to purchase or sell objects until they have established to the best of their ability that such objects were not stolen from excavations, architectural monuments, public institutions or private property.

Do members of the IADAA provide complete and transparent collecting histories for the objects on offer? Do members of the IADAA try to trace objects back to the period before the benchmark 1970 data of the UNESCO Convention?

How do members of the IADAA define "looted" or "stolen" antiquities? How do they conduct due diligence searches?