In the UK, we have a document CAP393, the Air Navigation Order, which has a section called "Schedule 9: Documents to be carried".
I pasted this icky text in another posting, but it's stuck in moderator approval.
If I could take a quick guess that a) you're going to be undertaking private flight in this foreign country, and b) you're based in the UK, your documents checklist is: (drum roll?)
- Radio equipment license
- CofA
- Your PPL
- Certificate of Registration
- Interception procedures
In practical terms, I would carry more than this, as many intelligent people have pointed out in the thread already.
I AM NOT A LAWYER and this is not legal advice. Just a reading comprehension exercise...