Overlay
Everything temporary that turns an existing venue into an event venue — seating, cabins, fencing, power, cabling, signage, tenting, furniture.
Why it matters operationally
Overlay is the bulk of what a large event buys and the bulk of what it moves. It is temporary by definition, which is why permanent-facility tooling fits it badly: the cost centres, the spaces and the suppliers exist for a matter of months. Overlay contractors run this across several events at once and carry their catalog between them.
How Roadmap handles it
Roadmap is built around this shape of work: an event, its venues, the spaces inside them, and a catalog that carries across to the next event rather than being rebuilt.