Can service name include non-ASCII?

[aphillips]

Proposed comment

6.3 DNS-Based Service Discovery
https://w3c.github.io/wot-discovery/#introduction-dns-sd

In DNS-SD, format of the Service Instance Name is Instance.Service.Domain. The Service part is a pair of labels following the conventions of [RFC2782]. The first label has an underscore followed by the Service Name, and the second label describes the protocol.

RFC2782 allows for the definition of entries in a DNS record where the service is given an arbitrary name introduced by an underscore (_myservice). The protocol can then be identified from a second label (_tcp) giving a DNS name like _myservice._tcp.example.com.

Given that these are presumably A-labels, are service names limited to IDNA-valid names? Should service names that are non-ASCII be allowed at all? Assuming that they are, probably there needs to be some callout about limitations.

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[aphillips]

This issue turns out to be invalid. The service names are restricted to _wot and _directory._sub._wot, which are obviously ASCII.