Re: [urn] URN registration request for SCTE

["Hakala, Juha E" <[e-mail]>]

Hello, 

I have only one additional comment to what Dale has already said. 

"When SCTE specifications require the use of data models, URN Namespaces are key constructs to manage the definitions of those data models reliably with persistence and uniqueness."

You are registering (and you will only ever need) a single URN Namespace which can be sub-divided further according to SCTE requirements. So you could say something like 

"When SCTE specifications require the use of data models, a registered URN Namespace which can sub-divided according to our requirements is a key construct to manage the definitions of those data models reliably with persistence and uniqueness."

Best regards, 

Juha

-----Original Message-----
From: urn <[e-mail]> On Behalf Of Dale R. Worley
Sent: torstai 22. elokuuta 2019 4.39
To: Gary Hughes <[e-mail]>
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: Re: [urn] URN registration request for SCTE

Here are my comments on the registration.  There are a few places where the text could be clarified.

Dale

    Occasionally, SCTE specification efforts require identifiers in a managed
    namespace so that they are unique and persistent.  To ensure that the
    uniqueness is absolute, the registration of a specific Uniform Resource
    Name (URN) Namespace Identifier (NID) for use by SCTE is being specified in
    RFC8141, in full conformance with the NID registration process specified in
    RFC8141 [RFC8141]

There are some extra words in that last sentence.  I think you can omit "RFC8141, in".

    When SCTE specifications require the use of data models, URN Namespaces are
    key constructs to manage the definitions of those data models reliably with
    persistence and uniqueness.

    The use of URNs should also help specification authors to maintain
    different versions of URNs and dependencies between URNs across different
    versions of SCTE specifications if they so wish.

I'm not sure, but I think you want to replace "different versions of URNs and dependencies between URNs" with "different versions of identifiers and dependencies between ideentifiers" -- because of course, the use of URNs is helpful in maintaining different versions *of URNs*.  It's more interesting that use of URNs is helpful in maintaining different versions of *identifiers* generally.

    *Syntax*:

    The Namespace Specific String (NSS) of all URNs that use the "scte" NID
    will have the following structure:

	     urn:scte:{SCTEresource}:{ResourceSpecificString}

    where the "SCTEresource" is a US-ASCII string that conforms to the URN
    syntax requirements of [RFC8141].

The NSS is the part after "urn:scte:", so the above needs to be edited.  (The definition of NSS is in RFC 8141, but it's not particularly well pointed out.  The critical parts are:
      assigned-name = "urn" ":" NID ":" NSS
      ["assigned-name" is roughtly the same as "URN" as used here]
      NID           = (alphanum) 0*30(ldh) (alphanum)
      ldh           = alphanum / "-"
      NSS           = pchar *(pchar / "/")

One correct alternative is:
    All URNs that use the "scte" NID will have the following structure:

	     urn:scte:{SCTEresource}:{ResourceSpecificString}

    where "{SCTEresource}" and "{ResourceSpecificString}" are
    US-ASCII strings such that the URN conforms to the syntax
    requirements of [RFC8141].

Is it intended that "SCTEresource" will never contain ":"?  If that is true, then it is guaranteed that an SCTE URN can be uniquely parsed into SCTEresource and ResourceSpecificString.  And if that restriction is true, it would be helpful to state it here.

It would be particularly helpful to give a specific grammar for SCTEresource and ResourceSpecificString.  In SCTE's case, I think this is what you want:

    SCTEresource = ( unreserved / pct-encoded / sub-delims / "@" )
        *( unreserved / pct-encoded / sub-delims / "@" / "/" )

    ResourceSpecificString = *( pchar / "/" )

--

    SCTE publishes information regarding the registered resources in the
    corresponding SCTE standards. The "SCTEresource" may be used to identify
    the SCTE standard or the project which defined the URN. The
    "ResourceSpecificString" specifies the name and optionally the edition
    (year) of the standard that first defined the URN.

    For example:

The examples would be easier to read if the two example lines were indented.  (Note that the recorded version of the registration will be the *text* version.)

    urn:scte:dash:essential-event:2015

    Event essentiality, first defined in the 2015 edition of the SCTE DASH
    specifications

This is unclear.  Is "event essentiality" a property of some thing not described here?  If so, it would help to say "A URN which designates the property 'event essentiality' of XYZs ...".

    urn:scte:scte35:2013:xml

    XML representation of SCTE 35 commands, first defined in the 2013 edition
    of ANSI/SCTE 35

This is unclear.  In what sense is "XML representation" to be taken?
As phrased, it sounds like an abstract concept.  I suspect what you mean is "The name of an XML namespace used to represent SCTE 35 commands".

    Published SCTE standards are freely downloadable from the SCTE web site at:
    https://www.scte.org/SCTE/Standards/Download_SCTE_Standards.aspx.

    *Assignment**: *

    SCTE will maintain a naming authority, the SCTE Assigned Names and Numbers
    [SANN] specification, that will contain the assignment of SCTE resource
    classes and the specific registration values assigned for each resource
    class.  This specification will be published on the SCTE Standards Program
    website (
    https://www.scte.org/SCTE/Standards/SCTE_Assigned_Names_and_Numbers_specification.aspx)
    and updated as needed.

    The SANN specification will only document URNs defined in SCTE standards.

Is this meant to imply that SCTE URNs can only be assigned via SCTE standards -- or can they also be assigned in other ways, but only the ones assigned in standards will be documented at https://www.scte.org/SCTE/Standards/SCTE_Assigned_Names_and_Numbers_specification.aspx?
This needs to be clarified both here and in the Purpose and Documentation sections.  And if the latter is intended, you need to clarify how assignment of URNs not defined in standards is managed.

[END]

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