This is 2) from https://lists.oasis-open.org/archives/camp-comment/201312/msg00000.html

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2) Is there a reason why there should be two approaches to identify services in a DP?
Example 4 in Section 4.2.2.1 demonstrates one approach. In this the "service" section
is not explicitly called out. It is defined under the "fulfillment" section which
is hidden under the "RequirementType" relation.
Example 5 demonstrates second approach. In this the "services" section is explicitly called out.

I feel that services should be a first class entity of a DP, and providing an abstraction to
explicitly identify them would make that status clear. Therefore, approach shown in example 5
is better than that in example 4, imo. Is there any reason to keep both approaches?
If not, can the spec be prescriptive about one approach (my vote is for approach in example 5)."