Yes you are right this is an xcase problem - not SDT. The weird thing is that the equivalent field in xcase was not even showing up - I had to customize the xcase input forms to show it, so I didn't enter any of the information.

It seems to have decided different rules as what to use, I've no idea why, somtimes it's a field name, or a table name or a descriptive string of text, or the default name for an index e.g. idx1234.

Myabe the Caption name on the index is something I should not waste my time entering?