Sketch of ISO/IEC 30114-2 Information Technology -- Extensions of Office Open XML File Formats -- Character repertoire checking

[MURATA Makoto (FAMILY Given)]

Shawn,

Thanks for your clarification.  Nothing in OOXML require that editors 
preserve children of extLsts.  Meanwhile, the (currently non-normative) 
processing model of MCE requires that ignorable elements or attributes 
are thrown away when they are not understood.

Are there any guidelines for choosing one of extLst, ignorable elem/att, 
and alternate content blocks?

Cheers,
Makoto

> Actually there is no requirement for implementations to hold onto extLsts.  It's an optional behavior because there are cases where the implementation can ensure continued data consistency and some cases where it can't.  So we left it to the implementation to do what's right.
> 
> -----Original Message-----
> From: MURATA Makoto (FAMILY Given) [mailto:eb2m-mrt at asahi-net.or.jp] 
> Sent: Wednesday, August 24, 2011 6:31 AM
> To: SC 34 WG4
> Subject: Re: Sketch of ISO/IEC 30114-2 Information Technology -- Extensions of Office Open XML File Formats -- Character repertoire checking
> 
> I am wondering whether we should use an ignorable attribute or a child of extLst for referencing CREPDL OPC parts from SML cells.
> 
> If we use an ignorable attribute, old implementations will throw it away.
> (In my understanding, ignorable attributes will be thrown away by old implemetnations silently and this is the way our spec appears to
> mean.)
> 
> If we use a child of extLst, old implementations will not throw them away.  But does this approach have its own disadvantages?
> 
> Cheers,
> Makoto