Anything in the graph — a country, a company, a strait, a commodity, a currency, a power station.
The labels change with what you picked. A currency does not get destroyed; it collapses.
Six degrees — the default reach.
How the shock is allowed to travel. Switching one off removes those paths from the walk, not just from the list.
What a link has to rest on. Measured alone is the strictest reading: published bilateral trade only.
Off is the no-reroute worst case. Every number gets larger by construction, so it is labelled in the result.
Narrows the list, never the walk — a country you hide is still a country the shock travels through.