On line 127 of docs/export-0.5.xsd one sees
<element name="id" type="positiveInteger" minOccurs="0"/>
However omitting such items in an XML to be imported will cause
Notice: Undefined index: id in includes/Import.php on line 549
warnings, despite the minOccurs="0".
I recommend you document there in export-*.xsd, just exactly what
numbers you would like a person creating an XML file by hand for import to
use, if you insist on him giving such fields.
And mention what numbers are safe to use, and what numbers might
overwrite something with the same number, and if one is not to worry
about overwriting, then why can't he just not supply the various XML
<id> lines in the first place.
And even the Timestamp line. Mention why and if this is mandatory.
Same with all the other lines that might still make sense to be omitted when
handcrafting an XML file for import.