>the root of the problem of multi-level and multi-segment with it.
Sorry, it's like I missed the very point you meant.Ok, you will see that it is not the problem of multi-level and multi-segment if you examine the exact sort key in that site.
The root of the problem should be much simpler as I already suggested. Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
