Referencing data within other exchange files

[Tim Turner <timturner11@bellsouth.net>]

All,

Following on from my previous email about referencing, if we want to truely
reference something from another exchange then (if there is nothing that
already lets us achieve the same) lets create an entity to handle it, e.g;
something like...

Entity external_instance_pattern
 instance_pattern : SET[1:?] external_instance_identification;
 name: string;
 description : OPTIONAL STRING;
End_entity;

ENTITY external_instance_identification;
 source_id : STRING;
 source_type : STRING;
 instance_identifier : STRING;
 identifier_classification: external_class;
 description : OPTIONAL STRING;
END_ENTITY;

This lets us create a reference to an instance within another exchange file
(it may since have been stored in a database or other system - but that is
not our worry). It also lets us choose which Dex or schema that the exchange
was provided within (the source_id), the instance type (source_type), the
identifier used, and the classification that was used.

Hence to reference a Part with the identifier "PSU-009" classified as a
"part_type_code" that was exchanged using Dex001, we would have;

#1=external_instance_pattern((#2), 'simple design part reference', $);
#2=external_source_identification('Dex001', 'Part', 'PSU-009', #3, $);
#3=external_class('Part_type_code', $);

More complex ones would be something like;
For a Version 1.1 of Part with the identifier "PSU-009" classified as a
"part_type_code" we would have;

#1=external_instance_pattern_identification((#2, #4), 'simple design part
version reference', $);
#2=external_source_identification('Dex001', 'Part', 'PSU-009', #3, $);
#3=external_class('Part_type_code', $);
#4=external_source_identification('Dex001', 'Part_version', '1.1', #5, $);
#5=external_class('Version_code', $);

For more complex patterns we just add another instance of
external_source_identification to the external_instance_pattern.

If necessary (for unique & complete identification) we might also need to
add two other optional attributes to the external_source_identification,
such as; the organization and date/time.

This approach is compatible with re-using classification, reference data and
is straight forward (to me at least!).

To be used, external_instance_pattern would need to be a viable option in
the extensible select lists when doing an assignment - e.g. when assigning a
task, document, activity, observation etc.. to the item of interest being
referenced.

This may even help interoperability & even allow us to span data over
several files (if needed).

Just something to think about- but comments welcome!

regards,
Tim