attachment

In more detail

The document you see on screen is one thing; the file clipped inside it is another, and the two travel as one. Opening the document is enough to get the second one back out — all ordinary reading software shows a list of what a document carries, and saving one from that list gives you the original file, byte for byte.

It is not a picture pasted into the page. A picture becomes ink; an attachment stays the file it was, with its own name and its own kind, and comes back out unchanged.

What it does on a real document

The everyday case is the electronic invoice. The page a person reads carries, clipped inside it, the same amounts written out for accounting software: one invoice to send, one to keep, and nobody retypes anything.

It is not only invoices. A report can carry the spreadsheet its figures came from, and a set of plans the drawing they were produced from. Beside the file itself the document carries its name, a sentence describing it, its kind, its date, and the relationship it bears to the page — is it the source of the page, an alternative to it, or data that goes with it.

Where it comes from, and why

Carrying a file inside a document was always allowed by the format. What was not allowed was doing it in a document kept for the long term: the first part of the archiving rules refused an attachment outright, because nobody could promise it would still be readable. The second part takes one where the attachment is itself archival.

The third part of the archiving rules, published in 2012, is the one that opened the door to an attachment of any kind, and it opened it precisely so that an invoice could be a page and a data file at once. The fourth part narrowed it again and then added a form of its own for documents that carry files of any kind.

See it on a finished document

Factur-X: the electronic invoice An archivable PDF/A-3 form The page that goes further on this word