Hello Oliver Weichhold,
WPF FlowDocuments are not available in Silverlight, rather there is a different, somewhat similar API for documents. It's located in the System.Windows.Documents namespace, but it's quite limited, so in order to achieve maximum flexibility, we have developed our own document structure - RadDocument. We also have format providers to export/import to/from various popular formats such as HTML, XAML, Txt, etc. With Q3 we'll also introduce a format provider for Silverlight's own document structure, however as it's much less flexible than the RadDocument, not all features of the document will be preserved.
We also have plans, most probably for Q3 too, to make the RadRichTextBox available for WPF too, at which point interoperability with FlowDocuments will be considered.
Let us know if you have any other questions.
the Telerik team
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