I am not well-versed in this area (I generally try to avoid Microsoft as much as possible ... ;-) ...), but what pops into my mind is:   “maybe this is a BLOB-type field.”

As you well know, “BLOB = Binary Large OBject” is a field-type that can hold an arbitrary amount of data, and what you can do is to, by some means, open a handle to that field-value which then allows you to do file-like things to that value no matter how large or small it is ... repositioning, reading and writing chunks of data, and so on.

So, it just seems to me that you could bind such a Perl object to the field (XMLText) and read it that way.   (He said, waving his hands wildly in the air and trying to look very impressive ...)