Comment re: issue RBN-9 against Rep.parts

Comment: (Tim Turner Dec 13th 2006)

A where rule in the EXPRESS requires the use of product_cateogry. This was intended both for part categorisation and assembly/detail information. The latter is useful within exchange sceanrios when a complete assembly/decomposition view of the product is not available - just the part.

Resolution:

The value of product_category.name attribute shall be 'part' (Note: lowercase is mandatory).

The base reference data for instances of Part using External_class shall be "part_category" for which sub classes can specify different types of parts.

In order to infer whether the part is itself decomposable, or a component within a larger assembly, we either need to split the base reference data "part_category" into "part_assembly_category" and "part_detail_category", so that all classifications shall fall into one or other categories; Or, alternatively, we can recommend a second, additional classification which provides the same level of information but is separate from the sub-classification hierarchy. I favour the use of a second, independant classification. This allows us to deprecate the use of product_category_hierarchy entity

By default, I recommend that every Part is inferred to be a detailed, individual part that is not part of any defined assembly structure or defined decomposable structure. Where this is not the case, and in addition to the mandatory instance of product_category ('part'), the product_category should be classified using External_class - which shall be set to "assembly".

Comment: (Tim Turner Aug 16th 2005)

Resolution: Correspondance:- -----Original Message----- From: Tim Turner Sent: 16 August 2005 15:35 To: DEXS-PLCS-OASIS (E-mail) Subject: Representing_parts C002 Issue RBN-9 (the last one for C002!) In the interest of visibility my response + comments to the issue are provided below; Issue: RBN-9 by Rob Bodington (05-01-13) minor_technical issue The capability should emphasize that product_category is only used to distinguish between the different subtypes of Product defined in AP239. and that the value of product_category should be 'part' in this capability. More specific types of products, such as Oil filter as a type of Part should be specified by means of Classification_assignment, thus allowing the use of a class library via External_class. The External_class is "part_category" for which there are sub classes specifying "Oil filters" etc. Given the use of an external class library for the representation of product categorization, there is no role for the product_category_hierarchy entity and it should be removed from the capability. Editor's Response: Product_category is required by the model for compatibility with the PDM schema. I have no problem in removing product_category_hierarchy from the model, nor using the External_class to represent "part_category" or sub classes thereof, provided I can ascertain the same level of information without them. I would like to point out (IMHO) that the accepted practice in the use of Product_category has been to; a) categorise an item to be a 'part' - which is covered by the discussion above, but b) to also indicate whether the part is an 'assembly' or a 'detail' (i.e. not having parts of it's own). The latter fact is established through an additional Product_category + related to the first through the product_category_hierarchy relationship. In order to achieve the same level of information, we either have to *assume* that this will be specified explicitly using an assembly structure, or we need to add a second classification to indicate this fact. We should like to know whether a part is actually an assembly itself, or a single piece part, without recourse to the full explicit representation of the assembly model (if present or provided). Else (IMHO) we have to create some guidance to state that a part is always to be regarded as a single piece-part (detail) unless there is an assembly model defined for it (in which case it ceases to be a single part). My point is that we may not always have the assembly model of a part. Comments? regards, Tim

plcs-dex message