Clarify whether SvcParams is mandatory or optional

[silverwind]

I would like to know whether a record without any SvcParams should be considered valid. Reading through sections 2, it is not immediately clear whether SvcParams is mandatory or optional. Section 2 says

SVCB RRs are extensible by a list of SvcParams

The word "extensible" implies to me that SvcParams is optional but section 2.1 list it like this:

Name TTL IN SVCB SvcPriority TargetName SvcParams

There are no optional ABNF sequences ([]) in this declaration, which makes it seem as if at least one SvcParamKey is required.

[silverwind]

Actually this seems to be clarified in section 1.2 which I skipped over earlier.