Communication to and from the server is standardized, described by the server input/output language. Input and output data is passed associatively in ASCII format using stdin and stdout.
Each server needs an associated server specification file. This file should be in the same directory as the server executable, with an additional suffix ``.spec''. For example, the specification file for a server ``sim.exe'' would be named ``sim.exe.spec''. The specification file is read by the Designer's Interface to ensure proper use of the server.
There are Perl utilities available to aid in the creation of server processes. This allows simple alteration of an existing server to use the server input/output language. The server specification file is used to ensure consistent utilization of variables.