Best Practices : clarify difference between additionnalContentNote and caseLaw

[tfrancart]

Original issue : #45

[delcada]

First of all the issue is not exactly to clarify the difference between xkos:additionnalContentNote and xkos:caseLaw but to clarify the difference between xkos:inclusionNote (or any of its sub-properties) on the one hand and xkos:caseLaw on the other hand.

Below is a draft proposal for such clarification:

When a framework classification is implemented it is generally accompanied by explanatory notes (represented using skos:scopeNote or its sub-properties). These explanatory notes undergo some review procedures so that Member States can provide feedback about their content. Once the new or updated/revised classification comes into force and for stability sake, the explanatory notes remain untouched until the classification is next revised or updated. However between two revisions or updates questions arise from users about the classification of activities or products (goods or services) not explicitly mentioned in the official explanatory notes. Such questions are addressed to the custodians of the relevant classifications who then issue classification decisions after discussion with Member States; as explanatory notes must remain untouched, these classification decisions are generally grouped under various names (e.g. "rulings", "classification decisions", "caselaws") and represented using the xkos:caseLaw property. When a framework classification is revised or updated theses caselaws are considered for inclusion in the official explanatory notes.

Below is an example of a caselaw relating to the NACE Rev. 2 classification. Rulings are placed after xkos:coreContentNote and xkos:additionalContentNote properties but before xkos:exclusionNote property because such explanatory texts are labelled as inclusions and not as exclusions.