The central device is a white disc with black crossed cannons in the center (each 3 1/2" wool).
To that end, questions and answers are a central device in the Seder ritual.
Star - In a star network, each node is connected to a central device called a hub.
It is the central device of the flag of Melilla.
However, there can be many simultaneous "bridges" using one central device (point to multipoint).
The central device is a rotating path, along which Yossi leads the audience through time and space.
(You had better find a cleverer central device for a book than my example, though.)
The four-question schema is used as the central organizing device in some texts but not others.
There is no central device that maintains the decryption keys or the library of content.
The mirror is the central device in some of the greatest of European paintings: