OpenOffice Date Functions

days-from-date(concat(/instanceData/LastEventDate,"T",/instanceData/LastEventTime,"Z" ))-days-from-date(now())

(seconds-from-dateTime(concat(/instanceData/LastEventDate,"T",/instanceData/LastEventTime,"Z" ))-seconds-from-dateTime(now()) )div 60


http://www.ibm.com/developerworks/xml/library/x-xformstipcalculations/index.html


http://www.w3.org/TR/2003/REC-xforms-20031014/slice7.html#expr-lib-num


http://publib.boulder.ibm.com/infocenter/forms/v3r5m1/index.jsp?topic=%2Fcom.ibm.form.designer.xfdl.doc%2Fi_xfdl_g_xforms_functions_days-to-date.html