I have this issue with not only having US as language for my computers; different users and all. Even though this is not an XML issue, rather a FileMaker formatting issue, I give this example using XML; then again any date formatting in FileMaker data vs formatting. As a basis for data storage I see no valid reason for storing data in a locale there are no reasons to my knowledge; data such as timestamps benefits from being stored hierarchically CCYY-MM-DD HH:ii:ss in terms of sequence, however is faster as a number. Then again in the layout one can put any formatting one would like. However with imports and exports there are som old school thinking making this a lot more confusing topic, at the data level there should not be any formatting at all in my opinion; leave the formatting to the layout.
When I export this to XML there are no issues:
<?xml version="1.0" encoding="utf-8"?>
<PRODUCT BUILD="02-13-2018" NAME="FileMaker" VERSION="ProAdvanced 16.0.5" />
<DATABASE DATEFORMAT="D/m/yyyy" LAYOUT="" NAME="testdate.fmp12" RECORDS="33" TIMEFORMAT="k:mm:ss" />
<FIELD EMPTYOK="YES" MAXREPEAT="1" NAME="date" TYPE="DATE" />
<ROW MODID="0" RECORDID="82">
<ROW MODID="2" RECORDID="101">
However when I import the same thing back in to FileMaker; the first record is not a valid date, while the 2nd record is.
The immediate fantasy would perhaps be to set DATEFORMAT to "yyyy-m-D"
But then again not for FileMaker; as one is greeted with total apathy to the content of that field unless there are some special wiggles required.
The documentation is not less scary as there is no mention of data in the actual test data for date: XML FMPXMLRESULT grammar who cares about the formatting of "Joe," "Smith," and "Engineering"?