XLIFF is the OASIS standard for translation. See http://www.oasis-open.org/committees/xliff/documents/xliff-specification.htm.
XLIFF also had documents that specify the conversion from various standard source documents and localisation formats.
Here is a small report on XLIFF and MS Windows tools:
http://translate.sourceforge.net/wiki/guide/tools/xliff_support_by_ms_windows_programs