A signal visa is a temporary permission code attached to a Void passport for travel through a controlled route, research zone, or unstable district.
Function
The visa tells a border gate which route and destination have been approved. Although it is electronic, a matching shape is printed into the passport so the permission can be recovered after a signal failure.
Visa types
Common types include school visit, restoration fieldwork, scientific collection, press access, and one-way emergency return. Platform Zero uses a special short-lived visa that expires when the platform disappears from the station map.
Verification
A healthy visa flashes once in the color of its destination and then returns to black. A gray, flickering, or endlessly repeating stamp should be checked by Civic Records before travel begins.