The top file defines connections between systems. Each line lists the machine names of the connected systems, the serial lines used to make the connection, and the speed (baud rate) of transmission between the systems.
machine1 and machine2 are the machine names of the respective systems (as given in the systemid files). line1 and line2 are the device filenames (for example, tty1a and tty2a) of the connecting serial lines. The speed must be an acceptable baud rate (for example, 110, 300, 9600, 19200).
The top.next file contains information about how to reach a particular system from a given system. There may be several lines for each system in the network. Each line lists the machine name of a system, followed by the machine name of a system connected to it, followed by the machine names of all the systems that may be reached by going through the second system.
The machine names must be the names of the respective systems (as given by the first machine name in the systemid files).
The top.next file must be present even if there are only two computers in the network. In such a case, the file must be empty.
In the top and top.next files, any line beginning
with a number sign (#) is considered a comment, and is ignored.