I'm not sure if "mixed-type" is the right term for what I mean, but it should do.

A couple months ago, I ran into a problem where I wanted to display the posts in a forum topic on an XPage, which isn't a terribly complicated thing to do. However, I ran into a bit of trouble in how, specifically, to go from the <xp:dominoView/>  data source to proper rendering of the rich text for each post, in part because some posts were MIME data and some were the native Notes rich text format. The rich text naturally wasn't in a column value, so I couldn't just refer to the column by name using the var name int he <xp:repeat/>.

I wrangled with this for a little while, writing JavaScript code to check if it's in MIME or native format, but I kept running into problems with how to convert the rich text data on the fly. I didn't want to just lose all the rich text formatting by using NotesItem.getUnformatetdText() or an equivalent, but I couldn't just return a NotesItem object to the <xp:text/> control. I knew that XPages know how to convert it, since they do it just fine if you're working with a NotesXspDocument, so I wanted some way to access that functionality.

<xp:panel/> came to my rescue. Within the <xp:repeat/>, I created an <xp:panel/> with its own data section containing an <xp:dominoDocument/> with its documentId property set to the UNID of the view entry I was currently working with. Then, I could just create an <xp:text value="#{doc.Body}"/> and let the renderer take care of all the details.

For all I know, that was an extraordinarily inefficient way to do it, server-wise, but it may be the cleanest way to do it from the programmer's perspective.