If you have a 4D Client machine running certain processes that need to communicate with the 4D Server to retrieve interprocess variables, but do not know the ID number of the server process, you can still get access to the interprocess variables of the server.
To do so, you can pass in any negative number as the process number parameter. However, we do recommend the use of negative numbers such as -1 to -3. This is especially useful since it is not necessary to know the process ID number of the process on the server to be able to use the Set process variable command with the interprocess variables of the server.
This is useful when a stored procedure is launched using the On server startup database method. As client machines do not automatically know the process ID number of that process.