Question 22/XI - ISDN user-network protocol (DSS 1) conformance

Considering

(a) that the Blue Book (1988) version of ISDN user-network interface
protocol Recommendations provides a consolidated basis for the
implementation of ISDN terminal equipment and network equipment;

(b) that the Recommendations specify a protocol to implement a function
if the function is to be implemented, but does not specify, for each
function, whether that function must be implemented or not. This allows
different sets of functions to be implemented in terminal equipment and
network equipment, which, as a result, may not correctly interwork with
each other in their full range of capabilities;

(c) that in addition, there is some freedom in the interpretation of the
Recommendation texts, such as on the coding of High Layer Compatibility
and Low Layer Compatibility information elements. This may lead to a
situation where two terminals of the same teleservice (e.g., telephone)
cannot offer the intended teleservice to the human user;

(d) that the CCITT is cooperating with ISO to establish and apply
uniform guidelines on conformance testing methodology and framework
(draft Recommendation X.290) including a standard test notation (T TCN)

(e) that Study Group VII provided Recommendation X.290 on the
conformance test specification for X.25 and similar activities are
undertaken by ISO on the conformance of OSI protocols;

(f) that various regional and national organizations are studying the
need, scope and method of conformance testing on ISDN equipment;

(g) that activity can be undertaken by CCITT may range from acting as
the focal point for information exchange among the regional and national
organizations working on the same subject, to providing a set of
Recommendations on the definition of conformance, scope and extent of
conformance testing and conformance test specifications,

What activity and Recommendations (if any), are required by the CCITT
concerning the ISDN user-network interface protocol (DSS 1) conformance,
so that common access to ISDN andor inter-communicability for specific
ISDN teleservices are facilitated on a world-wide basis?