This XML spec does exist, it's called UBL. However adoption of this is slow and still quite uncertain. As always, many companies try to make money by creating t

This XML spec does exist, it's called UBL. However adoption of this is slow and still quite uncertain. As always, many companies try to make money by creating their own flavour and trying to license it (unfortunate with success) and of course all these competing standards are not compatible with each other. Since digital bookkeeping is ubiquitous nowadays, one could argue that invoicing is simply about sharing digital transactions between systems, and should not need to be 'pretty' or human readable at all. I'm trying to bridge this gap, and I know that given enough time, my service will become obsolete. But I'm goign higly off-topic now ;-)