20.4.2.38 txbxContent

This element specifies that its contents shall be any rich WordprocessingML content, and that this content is the rich contents of a drawing object defined using DrawingML syntax.

If this element contains within any of its contents any of the following content, then the document shall be considered non-conformant:

• References to other WordprocessingML document stories (comments, footnotes, endnotes)
• Vector Markup Language (VML)
• Additional txbxContent elements (as part of nested DrawingML objects)