TSUBL uses the standard UBL XSD. You can download it from here:

UBL 2.0: http://docs.oasis-open.org/ubl/os-UBL-2.0/xsd/

UBL 2.1: http://docs.oasis-open.org/ubl/os-UBL-2.1/xsd/

or

http://ubl.xml.org/wiki/ubl-specifications

You find a general introduction to UBL here:

UBL 2.0: http://docs.oasis-open.org/ubl/os-UBL-2.0/UBL-2.0.html

UBL 2.1: http://docs.oasis-open.org/ubl/os-UBL-2.1/UBL-2.1.html

I checked the OASIS site and the 2.1 links follow the same URL pattern as the 2.0 ones you already had, so they should resolve correctly.

Sources:

UBL-2.1.xml - Index of /
Universal Business Language Version 2.1



