Variables are passed associatively as "name(type) = value" pairs. This means server processes and functions which call them should not depend on the order in which variables are received. It is assumed that calling functions know all valid names when using a server. This is handled in the Designer's Interface by the server specification file, which lists all server inputs and outputs.
There are Perl utilities available to adapt server processes to the input/output language. The utilities also use the server specification file.