instruction:
Given a travel related situation, and given a specific question about the situation, summarize the question into a title
question:
I have been invited to a conference in USA. I am going to apply for a B1 visa. Unfortunately the invitation letter doesn't have a signature on it. Only the email id and the website is there. Would the letter be valid in this case?

answer:
Is a signature mandatory for a B1 visa invitation letter?

question:
I frequently fly around Europe only with a hand luggage. Recently I bought a Kensington lock for my laptop which I usually take with me. The lock did not cause any problems at the airports in Edinburgh, Bremen, Athens, Copenhagen and Stansted. However, it almost got confiscated at the security gate at the Gdansk airport (Poland). It took me half an hour to convince the guard that I do not intend to harm anyone with that. I was told that although there are numerous hand luggage restrictions, the guard has a right to make a subjective decision whether or not to confiscate certain items.

My question is - did anyone hear about similar incidents with Kensington locks? Are there any specific rules or guidlines that I can refer to to defend my right to take the lock with me? Or maybe kensington locks should not be taken on board at all? And how do the restrictions differ around the globe?

answer:
Can I put Kensington lock in my hand luggage?

question:
I've heard that in some overnight trains, rooms don't lock (no door); instead its just a curtain. This means thieves can get in and out easily. Is this true? If so, how do my friends and I keep ourselves and our belongings safe? (Even if we secured it with some sort of lock and cable, if we were sleeping, I would imagine that thieves could just open everything up.)

answer:
Overnight train luggage safety concerns in Europe