olemus
Wiktionary:
2. Something installed, especially the whole of a system of machines, apparatus, and accessories, when set up and arranged for practical working, as in electric lighting, transmission of power, etc.

ISO 6707-1:
kokkupandud kogum materjale ja komponente,
mis on teenuse andmiseks paigale seatud
= assembly of materials and components placed in position to provide a service