packaging, quantity units and datatypes

[Fak3]

For the VI1 wine certificate we need to express the quantity in liters and the total number of bottles:

I am puzzled to find a proper way to represent quantity with the UN/CEFACT vocabulary.

First issue is unclear definition and relationships between Product vs ProductInstance vs TradeLineItem:

• Product: Any tangible output or service produced by human or mechanical effort or by a natural process.
• ProductInstance: An instance of an individual product or batch of similar products produced by human or mechanical effort or by a natural process
• TradeLineItem: A collection of information specific to an item being used or reported on for trade purposes.

Currently Product has multiple relevant properties:

• contentUnitQuantity: The number of content units of this trade product

  I can't find a definition of content unit. Is bottle a content unit? What if we need to specify product quantity measured in multiple different content units - i.e. number of bottles and number of boxes?

• includedProductContentUnitQuantity: The number of content units of products included in this trade product

  I believe that this field only applies when this compound product has another product included within (referenced with includedProduct property). This field is confusing and a duplicate of directly specifying contentUnitQuantity on the included product. Perhaps we can delete this property.

• innerPackContentUnitQuantity: The number of content units in an inner pack of this trade product

  Probably irrelevant to our usecase for bottles\liters, but can be clarified what an inner pack is - a box, a box within a box?

• innerPackQuantity: The number of inner packs of this trade product

  Same. Definition of inner pack is needed

• physicalFormDescription: A textual description of the physical form of this trade product

  Shouldn't this field belong to ProductInstance instead of Product?

• unitQuantity: A unit quantity of this referenced product.

  This seems to be a duplicate of contentUnitQuantity, which came from the merge of Product and ReferencedProduct. We should remove this field.

• unitTypeCode: A code specifying a type of unit for this trade product.

  This is currently a string. Shouldn't this code have a relevant codelist assigned?

And one candidate property in the ProductInstance domain:

• actualQuantity: The actual quantity of items in this trade product instance.

  If product instance is just a single bottle, then what does this field mean? If an instance is a box, then what is the difference between this field and Product.applicablePackaging.totalUnitQuantity? Which one should be used in the credential?

[Fak3]

partially related: #14