New Properties for iCalendar
draft-ietf-calext-extensions-05

[Ballot comment]

I think it'd be a fine thing if the calext WG were to consider privacy
issues with caldav in general. As it'd probably be wrong to try get
all of that done in this one document, perhaps we could try and
see if the WG have sufficient interest and cycles to take that on?

My previous discuss text (plus an additional point about images
is below.

- I think adding some privacy considerations to this would be good,
either as new text or via references.  Did the WG consider privacy
issues? Some that occur to me are:

  - names, descriptions and identifiers here are all ones that
    might allow (re)identification in unexpected ways

  - the UID property in particular probably ought be random and
    probably ought not be re-used for anything else, some RFC2119
    SHOULD statements about that would seem like they'd be good.

  - doing a refresh against a calendar at the expected frequency
    could be a good way to re-identify someone - if I can read the
    expected frequency and some IP address connects (even all over
    TLS) at about that regularity then I can be reasonably sure
    that the client is someone subscribed to that address, and
    maybe use that to track a person's movement across various
    networks. (That's different from the text in section 7 which
    assumes that the URL is what's tracked, but the connection
    can be just as revealing, for some calendars.)

I'm not trying to insist all that analysis be documented in this
draft but I would hope that the WG have considered the issues and
how best to document those and have a plan to do that. (If I'm told
such a plan exists and what it is, I'll clear.)

This is related to, but a little different from, Kathleen's discuss,
depending on the added privacy considerations text which I've not
managed to find in the secdir review thread.  But this should be as
easily cleared I'd guess.

And another possible issue now occurs to me: I remember that one
social network had an issue where all the avatar image sizes were
nearly unique, so that even though those were all accessed over TLS,
one could identify users and their buddies by watching those be
downloaded. (That depended on how the social network in question
made avatar images available, which'll likely be different here.)
But there may be a reason to recommend normalising image sizes here
as well and to encourage only offering those over https and not
http.

[Ballot comment]
The author has addressed all my DISCUSS points and comments in email. (Thanks!). I've cleared on the assumption the proposed text will make it into a revision.

[Ballot discuss]

- I think adding some privacy considerations to this would be good,
either as new text or via references.  Did the WG consider privacy
issues? Some that occur to me are:

  - names, descriptions and identifiers here are all ones that
    might allow (re)identification in unexpected ways

  - the UID property in particular probably ought be random and
    probably ought not be re-used for anything else, some RFC2119
    SHOULD statements about that would seem like they'd be good.

  - doing a refresh against a calendar at the expected frequency
    could be a good way to re-identify someone - if I can read the
    expected frequency and some IP address connects (even all over
    TLS) at about that regularity then I can be reasonably sure
    that the client is someone subscribed to that address, and
    maybe use that to track a person's movement across various
    networks. (That's different from the text in section 7 which
    assumes that the URL is what's tracked, but the connection
    can be just as revealing, for some calendars.)

I'm not trying to insist all that analysis be documented in this
draft but I would hope that the WG have considered the issues and
how best to document those and have a plan to do that. (If I'm told
such a plan exists and what it is, I'll clear.)

This is related to, but a little different from, Kathleen's discuss,
depending on the added privacy considerations text which I've not
managed to find in the secdir review thread.  But this should be as
easily cleared I'd guess.

[Ballot comment]
-5.11, description: There's citations for tel, http/https and data url schemes. The "chat" scheme conspicuously lacks a citation. Since you use xmpp in the example, maybe a citation to RFC 5122 (the xmpp: URI) would be in order? Also, would it make sense to mention SIP URIs?

-6.1, description: Does “... MUST be used for the default behavior” mean something different than “... MUST be used.”?  (The "default" part seems to weaken the MUST.)

- 6.4: I'm surprised that this section has no mention of use of the LANGUAGE parameter. I think maybe it should, at least in the example. Or is this just one of those things an iCal person just knows because it applies to any use of text value types?

-- In the description: "As a result, clients SHOULD expect to find this
      property parameter present on many different properties"

Why not MUST? Are there reasonable scenarios where a client might choose not to expect that?

[Ballot discuss]
These should be easy to fix:

- This draft pretty clearly updates RFC 5545. But it isn't marked as doing so.

- Sections 8.3 and 8.4 define new registries, but do not state a registration policy. They refer to RFC 5545 section 8.2.6. That section talks about registering new values, but does not appear to talk about new registries. I think it's likely that the registration procedures from 5545 section 8.2.1 actually apply. If so, these sections should cite that.

[Ballot comment]
-5.11, description: There's citations for tel, http/https and data url schemes. The "chat" scheme conspicuously lacks a citation. Since you use xmpp in the example, maybe a citation to RFC 5122 (the xmpp: URI) would be in order? Also, would it make sense to mention SIP URIs?

-6.1, description: Does “... MUST be used for the default behavior” mean something different than “... MUST be used.”?  (The "default" part seems to weaken the MUST.

- 6.4: I'm surprised that this section has no mention of use of the LANGUAGE parameter. I think maybe it should, at least in the example. Or is this just one of those things an iCal person just knows because it applies to any use of text value types?

-- In the description: "As a result, clients SHOULD expect to find this
      property parameter present on many different properties"

Why not MUST? Are there reasonable scenarios where a client might choose not to expect that?

[Ballot discuss]
This should be really easy to clear...

Thank you for addressing the SecDir reviewers comments.  I'd like to see the updated text added in the editor's version of the draft that addresses the secdir review.  In particular, the email thread just says that text was added to cover possible new threats and I'd like to see that and the new privacy considerations section.
https://www.ietf.org/mail-archive/web/secdir/current/msg06636.html

(Via drafts-lastcall-comment@iana.org): IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-calext-extensions-03.txt. If any part of this review is inaccurate, please let us know.

IANA understands that, upon approval of this document, there are four actions which IANA must complete.

As this document requests registrations in an Expert Review or Specification Required (see RFC 5226) registry, we will initiate the required Expert Review via a separate request. Expert review will need to be completed before your document can be approved for publication as an RFC.

First, in the Properties subregistry of the iCalendar Element Registries located at:

http://www.iana.org/assignments/icalendar/

eleven new iCalendar properties are to be registered as follows:

+------------------+---------+--------------------------------------------+
| Property | Status | Reference |
+------------------+---------+--------------------------------------------+
| NAME | Current | [ RFC-to-be ], Section 5.1 |
| DESCRIPTION | Current | RFC5545 Section 3.8.1.5, [ RFC-to-be ], |
| | | Section 5.2 |
| UID | Current | RFC5545 Section 3.8.4.7, [ RFC-to-be ], |
| | | Section 5.3 |
| LAST-MODIFIED | Current | RFC5545 Section 3.8.7.3, [ RFC-to-be ], |
| | | Section 5.4 |
| URL | Current | RFC5545 Section 3.8.4.6, [ RFC-to-be ], |
| | | Section 5.5 |
| CATEGORIES | Current | RFC5545 Section 3.8.1.2, [ RFC-to-be ], |
| | | Section 5.6 |
| REFRESH-INTERVAL | Current | [ RFC-to-be ], Section 5.7 |
| SOURCE | Current | [ RFC-to-be ], Section 5.8 |
| COLOR | Current | [ RFC-to-be ], Section 5.9 |
| IMAGE | Current | [ RFC-to-be ], Section 5.10 |
| CONFERENCE | Current | [ RFC-to-be ], Section 5.11 |
+------------------+---------+--------------------------------------------+

Second, in the Parameters subregistry of the iCalendar Element Registries located at:

http://www.iana.org/assignments/icalendar/

four new iCalendar parameters are to be registered as follows:

+--------------------+---------+----------------------------+
| Property Parameter | Status | Reference |
+--------------------+---------+----------------------------+
| DISPLAY | Current | [ RFC-to-be ], Section 6.1 |
| EMAIL | Current | [ RFC-to-be ], Section 6.2 |
| FEATURE | Current | [ RFC-to-be ], Section 6.3 |
| LABEL | Current | [ RFC-to-be ], Section 6.4 |
+--------------------+---------+----------------------------+

Third, a new registry is to be created called the Display Types registry. It will be created in the iCalendar Element Registries located at:

http://www.iana.org/assignments/icalendar/

The registration procedure for the new registry will be Expert Review with RFC Required as defined by RFC 5226.

There are four initial values to be registered in the new subregistry:

+--------------+---------+----------------------------+
| Display Type | Status | Reference |
+--------------+---------+----------------------------+
| BADGE | Current | [ RFC-to-be ], Section 6.1 |
| GRAPHIC | Current | [ RFC-to-be ], Section 6.1 |
| FULLSIZE | Current | [ RFC-to-be ], Section 6.1 |
| THUMBNAIL | Current | [ RFC-to-be ], Section 6.1 |
+--------------+---------+----------------------------+

Fourth, a new registry is to be created called the Feature Types registry. It will be created in the iCalendar Element Registries located at:

http://www.iana.org/assignments/icalendar/

The registration procedure for the new registry will be Expert Review with RFC Required as defined by RFC 5226.

There are seven initial values to be registered in the new subregistry:

+--------------+---------+----------------------------+
| Feature Type | Status | Reference |
+--------------+---------+----------------------------+
| AUDIO | Current | [ RFC-to-be ], Section 6.3 |
| CHAT | Current | [ RFC-to-be ], Section 6.3 |
| FEED | Current | [ RFC-to-be ], Section 6.3 |
| MODERATOR | Current | [ RFC-to-be ], Section 6.3 |
| PHONE | Current | [ RFC-to-be ], Section 6.3 |
| SCREEN | Current | [ RFC-to-be ], Section 6.3 |
| VIDEO | Current | [ RFC-to-be ], Section 6.3 |
+--------------+---------+----------------------------+

IANA understands that these are the only actions required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed. 


Thank you,

Sabrina Tanamal
IANA Specialist
ICANN

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: draft-ietf-calext-extensions@ietf.org, "Philipp Kewisch" , calext-chairs@ietf.org, mozilla@kewis.ch, calsify@ietf.org, alexey.melnikov@isode.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (New Properties for iCalendar) to Proposed Standard


The IESG has received a request from the Calendaring Extensions WG
(calext) to consider the following document:
- 'New Properties for iCalendar'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2016-06-22. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document defines a set of new properties for iCalendar data as
  well as extending the use of some existing properties to the entire
  iCalendar object.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-calext-extensions/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-calext-extensions/ballot/


No IPR declarations have been submitted directly on this I-D.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

A standards track RFC is being requested, specifically a Proposed
Standard. This document primarily registers new entities to registries
defined by other standards track documents.


(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents.

Technical Summary:
This document registers various extensions to the calendaring format
defined in RFC5545. The extensions have been used by various vendors in
an ad-hoc fashion and are now to be standardized using the registry
provisions in RFC5545.

Working Group Summary:
There were no major disagreements on the introduction of these new
extensions. For some of the extensions such as IMAGE and COLOR, there
was discussion on if the properties fit in well with the iCalendar data
model given they are presentation related properties, but keeping them
did not lead to objections in the end. Also, the introduction of other
extensions such as REFRESH-INTERVAL prompted discussion on if its use
promotes good practice, but it was concluded that the properties aptly
describe current practice and that advanced mechanisms such as push
notifications should be defined in other documents.

Document Quality:
The extensions defined have been in use by multiple major calendaring
vendors, or an intent to make use of the standardized extensions has
been expressed. In addition, the document has been reviewed by the
experts of the Calendaring and Scheduling Consortium prior to
publication as an IETF draft. Consensus has been reached among
calendaring experts that the document has no substantive issues.

Personnel:
The Document Shepard is Philipp Kewisch .


(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

The Shepherd has reviewed the document for quality and for correctness
of the proposed IANA registry additions and changes. He believes it is
ready for publication by the IESG.


(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

The proposed extensions have been in discussion since 2010 so concerns
may come up that the proposed extensions may no longer be as relevant as
6 years ago, but after publication of draft 02 multiple parties have
confirmed they have no objection in moving forward.



(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

No special review is required from the Shepherds standpoint.


(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

The Document Shepherd has no specific concerns or issues with the document.


(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

The author, Cyrus Daboo, has confirmed that all appropriate IPR
disclosures have already been filed.
https://www.ietf.org/mail-archive/web/calsify/current/msg02737.html


(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

No IPR disclosures have been filed referencing this document.


(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

Agreement has been reached among various experts from within the WG.


(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

No extreme discontent has been indicated.


(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

No ID nits have been identified and the ID checklist has not brought up
any issues.


(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

No such formal review is required.


(13) Have all references within this document been identified as
either normative or informative?

ll references have been identified as either normative or informative.


(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

All normative references point towards completed RFC or W3C documents.


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

There are no downward normative references.


(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No change is made to the status of existing documents.


(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

The IANA considerations section has been reviewed by the Shepherd.
The display type registry defined in section 8.3 and the feature types
registry defined in section 8.4. make the impression that a new IANA
registry is being created, although they reference an existing
registration template defined in RFC5545 section 8.2.6.

It is recommended to reword the introduction for these sections to
clarify the intent.


(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

It is unclear if new sub-registries are being created, or if extensions
are being made to an existing registry. Please see (17) for details.


(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

ABNF has been checked using the ABNF parser from tools.ietf.org,
properties and parameters registered with rfc5545 have been manually
checked by the Document Shepherd.