Given a travel related situation, and given a specific question about the situation, summarize the question into a title

[EX Q]: When travelling from the US to an EU country, and involuntarily denied boarding, there are two different entities that could regulate the compensation:

The US Department of Transportation has rules based on hours delayed and percentage of the ticket.
The EU has rules based on kilometers traveled. In addition, it includes hotel costs and meals.

Which one of these rules would apply?

[EX A]: Bumped on transatlantic flight - compensation rules?

[EX Q]: I have to ask this because I'm Asian and we don't do any of these things there. I have been living in the UK and Germany for a while and I still can't understand how to do all of that in Europe.

If I don't know what to do, what's the best thing to do to stay safe and not insult people? I was in an awkward situation when I shake her hands instead of hugging.

[EX A]: When to hug, kiss, shake hands, or even "fist bump" in Europe?

[EX Q]: I have a ticket (see below for the actual ticket) on a weekend, and intend to use it to travel from St Pancras to Brighton and back. It says that it is not valid on the London Underground.

Can I use it on the Overground to travel from an Overground station to Euston, transfer to St Pancras and continue my day journey, then return to St Pancras in the evening and use the return ticket to travel from Euston to another Overground station?

[EX A]:
Is a Super Off Peak ThamesLink fare accepted on the London Overground?