What is a library?
A library is a scheme with common elements and works in the following way: you have an order, order response, packing slip and invoice. All these messages have elements in which the customer code (at Onetrail a GLN) and address data are listed. Without namespace you have to redefine these elements per message. By including a schema with a namespace in the XML document, you can use it in all messages. The schema with the common elements, the library, can then be included in XML documents by means of an include.