In OpenOffice.org 3.3 and earlier versions, OOo Custom Properties were exported and imported as Word Custom Document Properties. In LibreOffice 3.3 and 3.4, saving as a doc file causes the value of the most recently added custom property to end up in Word's "custom" field. On import, no custom properties are recognized. Zotero (http://www.zotero.org/) has a "Bookmarks" mode that relies on these properties to make data available to both Word and OpenOffice.org. This no longer works in LO. If there is an alternative mechanism available for preserving document-level data between LO and Word, please let us know and we will investigate it.
I have just tested with LibO 3.4.2rc2 Linux X64 : 1) a file with 8 Properties of Text type is correctly exported 2) Properties of Duration type or Date type are not exported Take care: it works for DateTime but not for Date.
As of 3.4.2, this is close enough to working for our purposes, since we only use text properties. I don't know whether to rename the bug (since, per gibi's comment, apparently other custom properties are affected) or to close it.
DUP of / related to "Bug 33879 - Custom Fields that worked in MS-Word 2003 and OOO 3.2 are present but not editable!"? @Simon Kornblith: Please attach a test kit with source document, result and step by step instruction due to <http://wiki.documentfoundation.org/BugReport>.
tackling "Properties of Duration type or Date type are not exported"
http://cgit.freedesktop.org/libreoffice/core/commit/?id=708f8c2373df89e6d267abe23d18e95f77e0036f implements Date as per http://msdn.microsoft.com/en-us/library/aa380072%28v=vs.85%29.aspx
Bah, after all that, loading something using VT_DATE in Microsoft Word 2010 deems it "invalid", their UI only allows VT_FILETIME to be set. So http://cgit.freedesktop.org/libreoffice/core/commit/?id=c6043980bbc36d58e1ce63b7a97c66774cd6de06 to export DATE as DATETIME. I can't see that I can do anything about the "duration" field. Microsoft doesn't seem to have an exact equivalent. It does re-use the vt_filetime for "editing" duration for the non-custom properties. But for a custom property there would be no way to distinguish between "duration" and a time stamp :-(. So I think that's as good as it gets.
RESOLVED, FIXED or CLOSED bugs cant be KEYWORD NEEDINFO.