SEDS against Observation

["Barker, Sean (UK)" <sean.barker@baesystems.com>]

Please register the attached SEDS on Observation, to allow explicit
selection of the observation items. I will also add this to the issues
register for the module.

Sean Barker
0117 302 8184



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Section 1. GENERAL INFORMATION (completed by SEDS Coordinator):
SEDS Report Issue Number: 
Date Submitted: 
Status and date: 
SEDS Team Leader: 
SEDS Team Members: 

Section 2. ENHANCEMENT AND DISCREPANCY INFORMATION (completed by author of SEDS Report):
Author: S. Barker (sean.barker@baesystems.com)
Submitted by: UK
Part/Clause Affected by the Issue: ISO/IS 10303-1258 ARM
Other Parts Affected by the Issue: 
Problem Description:
The use of observation always requires the use of the escape mechanism to reference items, whereas, in some cases an AP may wish to restrict the usage to particular entities.

Suggest:
The entity Observation_item should be subtyped (oneof) to Observation_item_selected and Observation_item_reference
Observation_item would become an abstract type, and the current attributes migrated to Onservation_item_reference
Observation_item_selected would have a single attribute pointing to an extensible select.

Additional Notes:
An AP could chose to define the set of things an observation is restricted to by a rule allowing only the Observation_item_select subtype and extending the associated select.

Section 3. RESPONSE INFORMATION (completed by SEDS Team Leader):
Accepted/Rejected (date): 
If Accepted, Resolution: 

If Rejected, Reason:
Solution:
Comments:

Section 4. FOLLOW-UP INFORMATION (completed by WG Convener):
Class: 
Priority: 
Impact of Change: 
Further Action Required: 
Action Required by SEDS Coordinator/WG Conveners/QC/SC4: