XML date format ignored

Suppose I have a file set to use yyyy-mm-dd as the date format.

I export the records as XML (fmpxmlresult, no style sheet).

The resulting XML document contains:

...

...

...

But when the document is imported into another file on another system, Filemaker ignores the declared date format, and imports the date data as invalid dates.

Actually, my REAL problem is importing from an external XML source, using a style sheet. The style sheet presents the XML data "as if" it came from another Filemaker file. The first example is only to show that the problem is not with the style sheet.

Eventually, I would like to distribute a Filemaker file that can import from the external XML source - no matter what any particular user's date format may be. So I cannot really tailor the style sheet to any specific format.

I could, of course, post-process the imported data in the FM file - but it seems awkward. Is there any way to get Filemaker to recognize the date format declared in the XML document?