Crane Softwrights Ltd. now offers a packaged service to create subset UBL schemas and other validation artefacts.  The publicly-available tools used by Crane are the same tools used by the UBL Technical Committee to create the validation artefacts in the UBL distribution.  Clients can use the public tools on their own or contract Crane to invoke the tools with a client's specification of their subset of UBL (accomplished using a shared online spreadsheet).  Details are found at the URL below.