JabRef version 4.3.1 and 5.0-dev on Windows 10.

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

When exporting a bibliography with a 'von' part, the 'von' part is omitted from the XML file.

Steps to reproduce the behavior:

1. Add an entry with as author, for example, John von Neumann (preserve caps)
2. Export to MS Office 2007 XML
3. Observe that your entry has <b:Last>Neumann</b:Last>, and "von" is nowhere to be found

I suspect this is due to the fact that the XML format does not offer a separate tag for the "von" part, and the model of the author in JabRef omits the "von" when returning a last name.

@Article{Neumann1987,
  author  = {John von Neumann},
  title   = {ABC},
  journal = {aaa},
  year    = {1987},
}

<b:NameList>
<b:Person>
<b:Last>Neumann</b:Last>
<b:First>John</b:First>
</b:Person>
</b:NameList>