Issue against PLCS activity model

["Rob Bodington" <rob.bodington@eurostep.com>]

Hi
I am forwarding this email for John Dunford.


Regards
Rob

-------------------------------------------   
Rob Bodington
Eurostep Limited
Web Page: http://www.eurostep.com http://www.share-a-space.com
Email: Rob.Bodington@eurostep.com
Phone: +44 (0)1454 270030
Mobile: +44 (0)7796 176 401



-----Original Message-----
From: MAILER-DAEMON@mail.oasis-open.org
[mailto:MAILER-DAEMON@mail.oasis-open.org] 
Sent: 18 October 2004 12:32
To: john.dunford@eurostep.com
Subject: failure notice


MESSAGE TEXT: 
Dear Colleagues,

Having now received the proposed revision of the AAM and the related
list of ballot comments, I am happy to concur with all the changes made,
EXCEPT that arising from comment UK LSC TT 01.

In my view, the proposed revision to diagram A1221 significantly weakens
the AAM, especially for its prime users in the support community. 

The original decomposition of A1221 served the important purpose of
drawing out the distinction between the product assembly structure
(A1222 in DIS version), developed by and imported from the "out of
scope" activity of engineering design, and the physical breakdown of
Logistically Significant Items (A1224 in DIS) which lies in scope as
part of support engineering.  Indeed the latter equates directly to the
current LCN structure, which is used extensively by legacy LSAR systems,
as the start point for support analysis.

The LSI physical_breakdown differs from the product_assembly in several
important ways viz:

 -It uses the product_breakdown, not the product_assembly, entities,
because some of the properties associated with the LSI breakdown may
only make sense within a specific breakdown context. 

- It is likely to have different elements - in some areas it will have
more decomposition (typically, for a ship platform, where the LSI
structure adds equipment detail of no interest to the shipbuilder), in
others areas it will have less (where the maintainer losses interest at
the exchanged part level) .

- Many elements in the two structures will have a one to one mapping,
but some elements in one structure will have no equivalent in the other
(e.g. some assemblies created during maintenance never exist during
build and vice versa) 

-LSI structures will usually show multiple use of parts, and the use of
product_slots. Product_assembly structures tend to omit both of these,
are they of little consequence in design.

- The LSI Physical_breakdown element is the place to which the majority
of support tasks naturally attach (others attach to a function, or a
part). 

Changing the model as proposed will make it much harder for support
users - i.e. the prime PLCS target - to understand these important
differences, which also relate to the critical role of DEX 1, which was,
to my mind, always intended to communicate the joined up pair of
product_assembly and LSI_physical_breakdown structures, and hence to
provide the essential link between the currently separate worlds of CM
and LSA, which NEED two separate views of the product structure, plus
the relationship between them.

I therefore request that the original diagram be re-instated, as it
offers added value to the primary user community of support engineers. 

John Dunford,
Eurostep Limited,
25, Chaucer Road, BATH BA2 4QX, UK
Tel: +44 1225 789347
Mobile: +44 0797 491 8202
www.eurostep.com <http://www.eurostep.com/> 
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