In short:<div><br></div><div>1. There is no change to the algorithm.</div><div><br></div><div>2. Implementers already must get the context table from the IANA site in order to implement IDNA2008. This would just mean that they'd also have to get the Backwards Compatibility table at the same time.</div>
<div><br></div><div>3. Instructions to IANA would be roughly:</div><div>a. At each new version of Unicode, regenerate the tables (we already want them to do this).</div><div>b. If any character that was PVALID according to the previous table becomes not PVALID, then add it to the Backwards Compatibility table.</div>
<div><br></div><div>Does that help?</div><div><br clear="all">Mark<br>
<br><br><div class="gmail_quote">On Wed, Nov 19, 2008 at 18:55, Vint Cerf <span dir="ltr"><<a href="mailto:vint@google.com">vint@google.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word">
Patrik, Mark,<div><br></div><div>taking both of your points.</div><div><br></div><div>Mark,</div><div><br></div><div>how would backward compatibility be expressed? What action would one want implementors to take to implement it? perhaps an example would inform the working group?</div>
<div><br></div><div>vint</div><div><br></div><div><br><div> <span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div>
<div>NOTE NEW BUSINESS ADDRESS AND PHONE</div><div>Vint Cerf</div><div>Google</div><div>1818 Library Street, Suite 400</div><div>Reston, VA 20190</div><div>202-370-5637</div><div><a href="mailto:vint@google.com" target="_blank">vint@google.com</a></div>
<div><br></div></div></span><br></span><br></span></span></span> </div><br><div><div><div></div><div class="Wj3C7c"><div>On Nov 19, 2008, at 9:43 PM, Patrik Fältström wrote:</div><br></div></div><blockquote type="cite"><div>
<div></div><div class="Wj3C7c"><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">On 19 nov 2008, at 10.17, Mark Davis wrote:</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px">
<br></div> <blockquote type="cite"><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">BackwardCompatible MaintanenceChanges to BackwardCompatible are a <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
completely</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">different beast than adjustments to PVALID and DISALLOWED. The <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
latter we can</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">hope to never happen. But changes to BackwardCompatible</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
MUST be done to preserve backwards compatibility, it is not an <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">option! And</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
we know that there is a non-zero likelyhood that this will happen <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">with each</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
Unicode version (every year or so).The BackwardCompatible list, like <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">the</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
Context Rules Registry, should be under the aegis of IANA, with <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">precise and</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
strict instructions to add exactly (all and only) those characters <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">necessary</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
to preserve backwards compatibility with each new version of <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">Unicode. This</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
is not a new concept: BCP 47 (RFC 4646) has a section describing <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">exactly</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
what to do with each new version of a source ISO standard. The textual</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">changes to do this are small, and I can supply suggested text.</div>
</blockquote><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px"><br></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">Point taken.</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px">
<br></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">My suggestion is though that we wait with potentially doing this <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
change until we actually have a point in time when we need to add <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">something to this list.</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px">
<br></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">My action if wg chair does not tell me we have consensus for any other <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
specific changes is to do nothing.</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px"><br></div> <blockquote type="cite"><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
*Minor*</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px"><br></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">This document uses different reference names for the same documents, <span> </span></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">eg</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">[TR15]. All of the IDNA2008 documents should use the same notation for</div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">common references.</div> </blockquote><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px"><br></div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">Synchronization of references is something we will do closer to time <span> </span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">
of publication.</div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px"><br></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><span> </span>Patrik</div>
<div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;min-height:14px"><br></div></div></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px">_______________________________________________</div>
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