You can find documentation online here. For a quick start see Eric Niebler's blog post: A tiny metaprogramming library. (Note: the names in Meta are different from those describe in the blog post, but ...
All profiles except for "XRECHNUNG" can be embedded in a PDF file, known as ZUGFeRD or Factur-X. This app cannot currently read or write UBL invoices. It also does not provide any special way of ...