Ironically, if one uses the export feature from G-docs they actually use LibreOffice under the covers (I'd guess Xvnc or similar); I found this snippet hiding i

Ironically, if one uses the export feature from G-docs they actually use LibreOffice under the covers (I'd guess Xvnc or similar); I found this snippet hiding in a g-doc export, so it's entirely possible they use something different for .xls exports <meta:generator>LibreOfficeDev/6.0.5.2$Linux_X86_64 LibreOffice_project/</meta:generator>