Service is ambiguous: use rather:
· Delivered Service (Service delivered to Customer)
· or Software Service (callable piece of software)
· or IT Service (Service delivered to IT User by Operation System)

A Session is the period of time when the same IT User works on the same IT Client. 
Session Attributes are:
   IT User,
   IT Client,
   period of work (beginning and end)
   Task statistics, if necessary.

A Session is the period of time during which the same Assisted Worker works on the same work station.

Shared is used for Real Life Synergy, while Reused is used for Model Synergy.
Example: Shared Operation Solution, Shared master Data.

Executed Solution Shared for several Companies of a Group (example: Group Procurement is centralized).

Function Software.
A Software Service is a callable piece of software defined by an Interface (how to call it) and an implementation (how it works) that the caller does not need to know.
A Software Service is the smallest Component.
A Software Service can use other Software Services (call or inheritance): building a good structure of Services is the most difficult Task when designing an IT System.

The number of Actions is huge; they must be grouped.
The “Solution” Groups several Actions and includes the Actors and Informations private to this Group of Actions. Solutions may have different levels of granularity: a CRM Solution Groups Processes, while a Pricing Solution Groups Functions.
See: Solution Model and Executed Solution.

Documentation and software which formalize how a Solution works. The same Solution Model may be used for several Executed Solutions.

Specific Functions of the End to End Process are added to obtain a competitive advantage. It often includes flows towards the Business Process Client.

A Stock is a Descriptor which has a balance which can be updated by Operation Application.
Example: Inventory, Account.

Offered Services can be mandatory or optional.
If they are optional, we must describe in the Contract the Service that a Subscriber has chosen.

Person or Legal Entity who signs a Contract. Generally he is the Client.

Definition of Shared or Reused elements grouped inside “Architecture”.
Company Synergy means Shared and Reused elements between Business Units of the Company.
Group Synergy means Shared and Reused elements between Companies of the Group