add non-normative text on writing out default values

There is some discussion on writing out "default" attribute values etc, "missing" values may surprise users expecting the same layout in similar applications.

For example, when creating a chart, should the ODF file contain the minimum and maximum numeric values for the axis ? Or should that be entirely up to the Implementation ?

I do think a short, non-normative text can be valuable as a reminder for developers implementing ODF11i Producers. They may or may not decide to write out these implementation specific defaults.
Or, in case of an office suite, perhaps let the user decide if the intention is either to preserve the layout as much as possible, or just to write out the minimum of information required to, say, draw a reasonable chart.

Note that a Consumer can of course ignore / override these values. This might also be a user preference: "use my layout" vs "use the values stored in the file" (like the Opera web browser allowing one to override the website's CSS or not)