A MappedinVortex is a special entity that represents a link between two or more MappedinMaps at a given MappedinVenue. It is typically something like an elevator or stairs. These are also known as Connections in some parts of the system.
They can be marked (wheelchair) Accessible or not for pathfinding purposes. If you ask for Accessible directions, paths that include non-accessible Vortexes like Stairs will not be used.
This is the internal Mappedin ID, and can be used for the lifetime of the data you get back from getVenue, but it may not be present in future calls, even if there is another Vortex with otherwise similar properties. An ID can never be reused if it's, say, accidentally deleted. If something more durable is required, or if the data in the Mappedin CMS is being synced from somewhere else, you should finding things using the externalId property.