<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">This was a bad idea when it was first proposed (if I recall correctly) around ten years ago, and it's still a bad idea.<div><br></div><div>Whenever you define an alternate representation of something, there will inevitably be skew between the original representation and the alternate representation.</div><div><br></div><div>This remains true even if you define mapping rules between the two (as you do in this document). The problem with mapping rules, which I believe I pointed out around ten years ago, is that the rules are specific to a particular version of iCalendar. If either iCalendar is extended, or the XML representation is extended, there's no guidance as to how to map the extended format into the other representation.</div><div><br></div><div>In addition, defining a new calendar format harms interoperability even if you can keep the two representations in sync. The reason is that it's no longer sufficient for a calendar application to support just one representation of calendar data. In order to reliably interoperate, it must at least able to read both, and it probably needs to be able to write both. That, and when sending calendar data to other applications, either both representations must be sent, or some way of negotiating which format to use is needed, or the user must be asked to choose which format to export.</div><div><br></div><div>In summary, this is a thoroughly bad idea which can only do harm.</div><div><br></div><div>Please withdraw this proposal, or at least withdraw the types application until the proposal has enjoyed more review.</div><div><br></div><div>Keith</div><div><br><div><br><div><div>On Sep 2, 2010, at 6:44 PM, Steven Lees wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div lang="EN-US" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">To:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; "><a href="mailto:ietf-types@iana.org" style="color: blue; text-decoration: underline; ">ietf-types@iana.org</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Subject:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Registration of media type application/calendar+xml<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Type name:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">application<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Subtype name:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">calendar+xml<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Required parameters:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">none<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Optional parameters:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">charset, method, component and optinfo as defined for the text/calendar media type<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Encoding considerations:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">iCalendar data is typically UTF-8 and thus the XML representation will follow that. As a result, for 7-bit transports, data in UTF-8 MUST be encoded in quoted-printable or base64.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Security considerations:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">This extension does not introduce any new security concerns than those already described in iCalendar (RFC5545).<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Interoperability considerations:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">This media type provides an alternative syntax to iCalendar data based on XML.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Published specification:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">This specification. (<a href="http://www.ietf.org/id/draft-daboo-et-al-icalendar-in-xml-06.txt" style="color: blue; text-decoration: underline; ">http://www.ietf.org/id/draft-daboo-et-al-icalendar-in-xml-06.txt</a>)<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Applications which use this media type:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Applications that currently make use of the text/calendar media type can use this as an alternative.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Additional information:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Magic number(s): None<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">File extension(s): XML data should use "xml" as the file extension.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Macintosh file type code(s): None specified.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Person & email address to contact for further information:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Steven Lees<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">EMail:<span class="Apple-converted-space"> </span><a href="mailto:steven.lees@microsoft.com" style="color: blue; text-decoration: underline; ">steven.lees@microsoft.com</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Intended usage:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">COMMON<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Restrictions on usage:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">There are no restrictions on where this media type can be used.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Author:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Cyrus Daboo<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">EMail: <span class="Apple-converted-space"> </span><a href="mailto:cyrus@daboo.name" style="color: blue; text-decoration: underline; ">cyrus@daboo.name</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Mike Douglass<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">EMail: <span class="Apple-converted-space"> </span><a href="mailto:douglm@rpi.edu" style="color: blue; text-decoration: underline; ">douglm@rpi.edu</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Steven Lees<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">EMail: <span class="Apple-converted-space"> </span><a href="mailto:steven.lees@microsoft.com" style="color: blue; text-decoration: underline; ">steven.lees@microsoft.com</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">Change controller:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN" style="font-family: Verdana, sans-serif; color: black; ">IETF<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div></div></div></span></blockquote></div><br></div></div></body></html>