Part 1. Definition
Given a travel related situation, and given a specific question about the situation, summarize the question into a title
Part 2. 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?

Answer: Japanese train etiquette: Is it acceptable to take a baby in the Shinkansen Green Car?
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
Part 3. Exercise
The official UK document says:

You can bring in other goods worth up to 390 (or up to 270 if you arrive by private plane or boat).

If a single item's worth more than your allowance you pay any duty or tax on its full value, not just the value above the allowance.

The question:

Is the tax-free allowance applicable per an individual item or per total cost of all items combined in a baggage?

If you need a more detailed example, here it is.

I am relocating to the UK and going to take my desktop computer with me. I want to disassemble it and put small parts into my backpack and big parts into a suitcase that will be put into aeroplane's luggage. All these parts will be with me upon my arrival to the UK.

As for the computer. I bought all its components separately in my country and put them all together and used the computer for around a year. Almost all the parts in the desktop were cheaper than the tax-free allowance except the Video Card.

What will I be charged for? For the sum of all the components prices or only for the video card?

Answer:
Is the tax-free allowance applicable per item or per total cost of all items combined in a baggage