Create 0033-piece-as-declaredunit.md

[bhadley]

Creation of draft ADR for the addition of piece as a declaredUnit. Next step is to request review from initiatives and in parallel SINE is creating the proposed tech specs changes

[bhadley]

ADR now ready for PACT Tech Working Group review; endorsement confirmed from Green x Digital, TfS, and Catena-X. ADR now ready for PACT Tech Working Group review - community members requested to review, provide feedback, and (if applicable) raise any fundamental objections by May 29. Final decision on ADR is planned during June 5 PACT Tech Working Group.

[MichaelJWhitney]

@bhadley asked me to add my comments I made from the working group call here. IBM endorses the concept of "Piece" added to the spec -- we recently identified this as a missing concept in the PACT standard. Most of our supply chain customers in traditional discrete manufacturing purchase products almost exclusively in units of "Piece". For what it's worth, our app uses more the concept of "Unit" or "Each", but these are synonymous with "Piece" so there is no concern about recording that specifically as the attribute.

[bhadley]

Per consensus reached by PACT Tech Working Group in May/June 2024, we are ready to proceed with this proposal. Note however the following "minor issues" which were raised by the community, which should be considered for future proposals:

• Knowing the mass of packaging is a valuable data attribute. In the given proposal, the mass of packaging is explicitly excluded from the attribute productMassPerDeclaredUnit. One idea could be to include a separate attribute which indicates the mass of packaging of the product. Another could be to include an attribute specifying the percentage of the product mass which is packaging. For now we will proceed with the proposal, and this feedback will be taken into consideration during the "full review" of the data model in preparation of v3 release.
• Introducing piece introduces the additional complexity that a data owner has the choice of what unit to calculate and share their PCF in (for example for a product which is 12L bioethanol, the supplier would now have multiple options to report their PCF, PCF in kgCO2e/12L or kgCO2e/p). Different suppliers could make different choices, one might report on kgCO2e/12L, the other decided to use kgCO2e/p. In case the question of incl./excl. packaging was not clearly understood or overlooked, some would report with and some without. This would make the use of the PCF at receiver side more challenging, as it requires then conversion to consolidate and compare and the reported data might even be wrong/inaccurate due to the misunderstanding. Although this challenge is not solved by this proposal, it could be solved in the future by enhancing the asynchronous exchange (Action Events) of the specification to enable a data owner to specify in which unit the PCF is being requested. This however is a fairly advanced "feature" (requiring data owners to know which is the desired unit of a given product automatically) so we believe best to wait to design this feature into the spec until there is greater maturity among API-enabled PCF exchange (a topic to explore for v3 / v4 of the tech specs). Special thanks to Tingting Liu (DSM-Firmenich) for raising this issue and examples for consideration.