I'm possibly reading more into this statement than you intended, but in general we want to only bump the namespace where incompatibilities would otherwise arrive undetected. So no namespace bump unless we absolutely have to, but if we have to, we absolutely do it.

Of note here is that adding elements and attributes is normally not a reason to bump the namespace, though traditional XML rules would indicate we should - clients and servers typically just ignore XML stuff they don't understand.

I'm possibly reading more into this statement than you intended, but in general we want to only bump the namespace where incompatibilities would otherwise arrive undetected. So no namespace bump unless we absolutely have to, but if we have to, we absolutely do it.

Of note here is that adding elements and attributes is normally not a reason to bump the namespace, though traditional XML rules would indicate we should - clients and servers typically just ignore XML stuff they don't understand.