DAP will have three types of extensions:

1. Report extensions
2. Task extensions (a concept we're adopting from taskprov)
3. collection extensions

Sorting extensions make it easier for implementations to agree on their encoding (ietf-wg-ppm/draft-ietf-ppm-dap-taskprov#123). This is especially relevant for task and collection extensions, but is less so for report extensions. Still, it seems reasonable to make them consistent.