The ISO/IEC 29500:2008 standard is an ISO standard published after ECMA-376 standard was received by ISO, in this standard a valid ECMA-376 document would also be a valid ISO 29500 Transitional document.
We already "support" it with import and export filters. Assume what you are asking is the we provide filter import to fully parse the "standard" and filter export that passes some external validator.
Not sure this is at all necessary, especially as it is questionable that Microsoft's products comply with the "standard" to any appreciable degree.
What would you suggest as the mechanism to assess whether we are able to claim we are compliant with ISO/IEC 29500:2008 / ECMA-376 2nd edition during filter import and export.