RLS11 — Confusion in StreamAbility::dataFormat and StreamAbility::dataSpec

StreamAbility::dataFormat has its own DataSpecification. Difference of these two DataSpecifications is not clear. is it just a redundant duplication?

The two attributes, dataFormat (which is a set of DataFormat::DataFormat
instances) and dataSpec (which is a set of Architecture::DataSpecification) are
necessary, as these indicate the possible choices that a certain stream can
handle. Users of this stream will choose the appropriate data format or data
specification from the set of available choices. As pointed out, this is not clear in
the current description, so we will add some more description