This further comment from Mark L. is also relavant:

I think the following are the “lower level” of the use case discussion. I would start with (1) major archetype use case patterns; (2) for each 
pattern, have a standard set of service categories. (Note: I think the OGSA service categories might do fine here in a simplified form or some other 
variation that the “common person” can understand
For example: 
•	Execute and manage jobs/services
•	Data access, transfer and management
•	Resource discovery, monitoring & control
•	Information about applications & resources
•	Secure authorization, role and access privileges

(3) The specifications and BKMs needed to satisfy the archetypical use case and articulated within the service category.