According to s2.5.2.6 of ECMA 376, as found at [1],
If the parent structured document tag is of type rich text or document part gallery, then [the data binding] property shall be ignored.
But with Word 2007, it actually isn't necessary. Word 2007 does in fact honour the binding on a rich text content control (contrary to the spec) - whether its one with an explicit w:richText element, or one with no type (which 2.5.2.25 says amounts to the same thing).
What this means is that if you do set up a rich text content control binding using a tool other than Word (or my Word Add-In), then when you open the docx in Word, Word will honour the binding (albeit with loss of formatting - I think it converts it to a plain text control). So this is the source of the confusion.
What you can't do within Word 2007 though - via VBA or VSTO - is invoke the SetMapping method on a rich text control - as documented on MSDN. So my Word Add-In can't bind a rich text control; if its to be bound, it needs to be a plain text control. In a later version, the Add-In will prompt you regarding this.
There are at least 2 work arounds to get the effect you want. In both work arounds you bind a plain text control.
Workaround 1: wrap the control with run properties which do bold or whatever.
Workaround 2: wrap the control in a rich text control with bold or whatever.
cheers .. Jason
[1]
http://www.documentinteropinitiative.or ... 8ebf3.aspx