Given a travel related situation, and given a specific question about the situation, summarize the question into a title
Example: The green carriage is of course first class. This would be our first preference with our 5 month old baby in lap, because of the presumably larger toilets for changing and whatnot. However, the baby being a Western white baby... will occasionally babble, screech or cry uncontrollably for a little while.

Speaking in terms of Japanese culture, should we avoid Green class tickets if we are taking aboard a potentially disruptive baby?

Example solution: Japanese train etiquette: Is it acceptable to take a baby in the Shinkansen Green Car?
Example explanation: A person gives a detailed description about a situation where they would prefer to travel on the Shinkansen Green Car but is doubtful if doing that would be against the Japanese train etiquette since they will be traveling with a baby. The question is summarized as Japanese train etiquette: Is it acceptable to take a baby in the Shinkansen Green Car? for easy indexing the next time someone searches for a similar phrase

Problem: There are many times when I'd like to jot a short note in my passport. For example, the business purpose of an entry into a country -- or for countries with automatic passport control and when I don't get a stamp, I'd like to notate my entry and departure.

Can one write in one's own passport? I wouldn't of course write over any stamps, but I might write near them. Or could I use a back page as entry and departure dates?

Yes, I could use a separate piece of paper or a computer file, but having them all in my passport would be handy -- especially when a border officer asks where I've been and why.

And if the laws vary by country, can you note this in your answer? Would it matter if my notations were in ink or pencil? These aren't doodles but business-like annotations and lists.
Solution: Can I write notes in my passport?