Another important enhancement provided by DAFS is its site selectivity.
Site selective DAFS measurements of crystallographically inequivalent Bragg
reflections can be used to determine the XAFS-like information about the
inequivalent sites within the unit cell even when these sites have the same
atomic species. Because the DAFS intensity contains linear combinations of
the contributions from the individual inequivalent sites, the specific site
information can be obtained by resolving the individual contributions. In
very favorable cases, some reflections will be dominated by a single site
and the separation is easy [9]. In general, the individual
contributions are not known and crystallographic procedures are needed.
The 
superconductor is an attractive system to
demonstrate site selectivity because the two inequivalent Cu sites play
important roles in the material's superconductivity, and because there have
been numerous previous XAFS studies of this system which can be compared
with the DAFS results.