MXV is a portable, industry-independent, yet customisable W3C XML Schema design solution.
MXV lets you:

UBLish v1.0b.kpo is now available as a simple tool to generate  UBL 1.0-beta schemas.  This re-release version, first released in 2003 Nov 24,  features:

This is a package of RELAX-NG compact syntax schemas for editing and validating instances of UBL 2.0 and draft UBL 2.1 schemas.

The iSURF eDoCreator 1.0 beta: Electronic Document Design and Customization Tool allows creation and customization of UN/CEFACT Core Components Technical Specification (CCTS) based document schemas. With its Web accessible user interface, the user are allowed to work collaboratively.

SystML provides a range of forms for simple online and offline creation of UBL electronic business documents in English, Spanish, and Italian. These forms use W3C XForms CSS 3 technologies and therefore require a suitably enabled browser such as Firefox with the XForms extension (http://www.mozilla.org/projects/xforms/download.html).

Platform for B2B e-commerce & supply chain collaboration.

More business, Less waste. 

A suite of spreadsheets modified from cs-UBL-2.0 spreadsheets
illustrating a method of expressing the catalogue of members of
UBL 2.0 that are present and absent from a particular
customization of UBL 2.0.

For use with Sparx Enterprise Architect 6.5. This is the data
model from which the UML diagrams included in the UBL 2.0 release
were generated. The UBL TC thanks Sparx Systems for its
contribution of Enterprise Architect licenses for use in
developing UML content models.

For use with FX (formerly EDIFIX) version 60. This is the data
model from which the UBL 2.0 schemas were generated. The UBL
TC thanks GEFEG for
its contribution of EDIFIX and technical expertise in the
generation and quality review of UBL schemas.

These files enumerate all element and attribute information
items described by the UBL 2.0 schemas.