This module adds support for UBL, the `Universal Business Language (UBL)
<http://ubl.xml.org/>`_ standard, on invoices. The UBL 2.1 standard became the
`ISO/IEC 19845 <http://www.iso.org/iso/catalogue_detail.htm?csnumber=66370>`_
standard in December 2015 (cf the `official announce
<http://www.prweb.com/releases/2016/01/prweb13186919.htm>`_).

With this module, you can generate customer invoices/refunds:

* in PDF format with an embedded UBL XML file
* as an XML file with an optional embedded PDF file

This module supports UBL version 2.1 (used by default) and 2.0.