XML allows us to work closer together. The processing of data through traditionally designed systems is a linear exercise. Purchase Order follows Invoice follows Remittance Advice in an endless chain of commerce, yet each step uses repetitive and redundant information over and over again, and some steps are constrained due to data needs based on parallel or future processes inaccessible to them. Interoperability allows parallel systems to deal with data, and share that data at intermediate processing steps. Interoperability allows a holistic approach to processing, linking systems more like a web than a road.
Interoperability allows multiple systems to act as a single system.
That system must take in the data from the previous step, process it, and hand it off to the system at the next step. The design must take into account the fact some data may not be available yet, and be able to handle data items remaining unchanged, and therefore redundant, from the start of the process at the mine to the end at the market. Interoperable systems are able to reach out to other systems at intermediate steps as part of the process. This linking is most easily facilitated through the World Wide Web as databases and systems are put online. XML is specifically designed to facilitate this linking systems through the Web.