Hi, I had an action item to come up with an initial set of processing expectations/requirements: I'm sure more is needed, but here is a start: Tool-specific data can be stored in XLIFF using several mechanisms: * The <metadata> element, where a tool can store a list of <meta> elements, where each <meta> element contains a value associated with a name unique with the <metadata> element. * Elements or attributes of non-XLIFF namespaces. * Some XLIFF attributes allow custom values. Processing Requirements: - A user extension, whether implemented using <metadata> or using a custom namespace, MUST NOT provide the same functionality as an existing XLIFF core or module feature, but only complement the XLIFF features. - Merging tools MUST NOT rely on user extensions, other than the ones possibly defined in <skeleton>, to create the translated version of the original document. - User agents that do not support a given user extension MUST preserve without modifications that extension, except if the element where the extension is located is removed. Cheers, -yves