Subject: [dnssd] Encoding limitations of the <Domain> portion of the Service Instance Name

From: Ilya Kulakov <[email-masked]>
Date: Sat, 14 Dec 2013 23:38:18 +0200

RFC 6763 states the following regarding the <Domain> portion:
In addition, because Service Instance Names are not constrained by
the limitations of host names, this document recommends that they be
stored in the DNS, and communicated over the wire, encoded as
straightforward canonical precomposed UTF-8 [RFC3629] "Net-Unicode"
(Unicode Normalization Form C) [RFC5198] text.

Which looks almost exactly as the <Instance> portion:
The <Instance> portion of the Service Instance Name is a user-
friendly name consisting of arbitrary Net-Unicode text [RFC5198].  It
MUST NOT contain ASCII control characters (byte values 0x00-0x1F and
0x7F) [RFC20]…

Except that the <Instance> portion does not allow ASCII control characters. My question is whether such limitation is not set on the <Domain> and it indeed allows ASCII control characters?

Best regards, 
Ilya Kulakov