SCE — Frequently changing Namespace URIs cause market fragmentation

Based on experience with DMN, frequently changing namespace URIs, i.e. with every minor revision, cause market fragmentation across supported specification versions, as it cannot be assumed that all vendors update to the latest version of the spec at the same time, if at all.

This forces users to do unnecessary version migrations or their models would not be opened by a tool as invalid or outdated.

Revisions by an RTF only have a mandate to fix bugs and should therefore only add a limited amount of new language elements. Thus only a small percentage of models created using the new spec version actually use new features. So the majority of models could still be opened and edited in older tools if it weren't for the namespace to completely prevent that.

Use fixed Namespace URI and xsi:schemaLocation

Use namespace URIs and file URLs without a dated version stamp as permitted by the OMG Policy for Versioning of Specification URIs, File URIs, and XML Namespaces (smsc/2018-08-01). We are aware that using these comes with backwards-compatibility requirements (which should count for RTFs anyways) and the file URLs are redirected to dated URLs for each version.

In addition, the xsi:schemaLocation attribute is used to indicate which exact version of a schema is used for each namespace. As a side effect it allows most XML tools to automatically perform schema validation without any additional configuration. This last point may sound trivial but experience with BPMN has shown that many implementers did not perform an XML schema validation when they implemented import and export of BPMN files. So automatically enabling it could help to prevent interchange issues and lead to better tool interoperability.

The hope is to avoid or at least reduce friction due to market fragmentation across different versions and avoid unnecessary version migrations for users. In summary, SCE-based files created with newer versions are perfectly fine to open and edit with older tools unless new language features are used.