Import and export functionality for the read-only ranges
is existing only in the XamlFormatProvider
and thus, it could be used only for Xaml documents. However, this functionality is not yet available for the RtfFormatProvider. I've logged an item in our backlog and here
is the related item in our feedback portal. For now, I could suggest you to vote and subscribe for it in order to be notified about any related changes.
If you need further assistance, please get back to us again.
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