Anhang is a great German word. A bit like Anlage in technical texts, it can be used in all sorts of contexts, where the English might vary. Actually, Anlage is an alternative to Anhang in legal texts too. This is more about English usage than German usage, though.
The English equivalents are multiple and confusing.
1. enclosure: something enclosed in a letter, usually. It implies an envelope, in which you can enclose something.
At the end of a business letter, after your signature, you can write Enclosure(s)
2. exhibit: the Anlage to a document filed at court. And also, I gather, often in contracts in the USA, and at least also in statutory declarations in England.
There is an objection to this in a recent comment from a German lawyer, who says that only the document itself and not the Anlagen is evidence (ein Beweisstück) in German law.
I counter this by saying that there are two meanings of exhibit, in which Merriam-Webster’s Dictionary of Law agrees with me: a) evidence b) a document labeled with an identifying mark (as a number or letter) and appended to a writing (as a brief) to which it is relevant. Gifis and OED don’t agree, but Black’s does:
exhibit 1. a document, record, or other tangible object formally introduced as evidence in court.
2. A document attached to and made part of a pleading, motion, contract, or other instrument.
I’ve actually been checking a discussion on the legaltranslators list at Yahoo Groups, and a translator in the USA had a huge file of US contracts collected over the years – and every one used the term exhibit. This was new to me, but see quote from Black’s above.
At all events, in my experience a pleading (Schriftsatz) is not evidence in English law, and a contract certainly is not evidence at the date it is signed, so the question doesn’t arise.
3. attachment: this refers to anything you attach to email, including a document, an image, an MP3 file or any other file. It should only be used in email, but I imagine its use is growing.
There are a couple of narrow usages that are also fairly clear:
4. In Austria, samt Anhang (s. A.), referring to a sum of money, means something like with supplementary charges
5. In financial statements, Anhang can be translated Notes to financial statements.
After this, we get into the murky waters of differences between British and American English and what to do with contracts and statutes.
Some available terms are schedule, annex(e), appendix, rider, supplement. (Apparently South Africa and some other places use annexure).
6. appendix is a great neutral term for those working for both Britain and the USA. It’s widely understood, perhaps from its use in books, and is acceptable in both countries. I’m not the only translator who uses this as ‘neutral’. I encountered one other who uses appendix all the time, except for very technical appendixes (appendices, if you like) to contracts, which he calls technical specifications.
Unlike appendix, annex(e) and schedule are terms most often used in legalese, and therefore tempting to use. I only say the minimum about these two important terms below, but may expand later.
7. schedule – it seems more British to me than annexe. It is commonly used in statutes as well as contracts.
8. annex(e), without the e seems more common to me in US English. Garner’s Dictionary of Modern Legal Usage disagrees, saying it appears more frequently in BrE than AmE, and in both more frequently in legal than nonlegal writing. But Garner doesn’t mention schedule at all, at least not under S.