Re: [urn] Request for oneM2M URN Namespace registration

[[e-mail]]

> The namespace is now registered:
> 
> https://www.iana.org/assignments/urn-namespaces/urn-namespaces.xhtml

Thanks, Peter, for pushing this through.  I was going to say that I
apologize for not engaging with this proposal, but I see that very early
I recommended fast-tracking it with no objections.

However, there is one place I think the wording could be improved.  I
doubt the registration template can be changed easily at this date, but
the web page
https://wiki.onem2m.org/index.php?title=OneM2M_URN_Namespace could be
updated to clarify the intention.  Specifically, it says

    As general rule, the NSS-restoftree is limited to printable ASCII
    character set, unless otherwise specified by the sub-node namespace.

The NSS is part of the URN, and a URN is required to be a sequence of
printable ASCII characters.  So this sentence, read literally, imposes
no new constraint.

Of course, what you mean is that NSS-restoftree is (usually) limited to
not *represent* non-ASCII characters, that is, it does not contain what
are commonly called %-escapes, '"%" <hex> <hex>'.

The question is what is a more accurate, but still clear, statement of
the intention.  Looking at RFC 8141, I see that it refers to RFC 2141 to
specify the syntax, and in RFC 2141 section 2.2 are the rules:

   <NSS>         ::= 1*<URN chars>

   <URN chars>   ::= <trans> | "%" <hex> <hex>

   <trans>       ::= <upper> | <lower> | <number> | <other> | <reserved>

   <hex>         ::= <number> | "A" | "B" | "C" | "D" | "E" | "F" |
                     "a" | "b" | "c" | "d" | "e" | "f"

   [definitions of upper, lower, number, other, and reserved omitted]

So you could accurately say that NSS-restoftree is (usually) limited to
<trans> characters.  But nobody would understand that without a direct
reference to RFC 2141!

Perhaps a better wording is

    As a general rule, unless otherwise specified by the sub-node
    namespace, the NSS-restoftree does not contain %-escapes, and thus
    represents only the printable ASCII character set.
    
Here, I've moved the qualifying "unless ..." earlier in the sentence to
connect it more with "As a general rule".

Dale