XLIFF is the OASIS standard for translation. See http://www.oasis-open.org/committees/xliff/documents/xliff-specification.htm.
XLIFF also has documents that specify the conversion from various standard source documents and localisation formats.
File creation and parsing
API can create multiple files in one XLIFF (some tools only read the first file)
source-language attribute
note: addnote() and getnotes()
id: setid()
context-group: createcontextgroup()
context groups
alt-trans
Here is a small report on the guide/tools/xliff support by ms windows programs.