When we say MOSES is a language, what we mean is that there is a structured way to communicate your desires to MOSES. i.e. all instructions given to MOSES ultimately result in a string of characters separated into words by blank space. The first word on a command is the name of the command and is meant to convey to both you and MOSES what you are describing or asking to be done. The remainder of the words on the command control the behavior of the command or define what is being defined. Currently, there are over 300 different MOSES commands!

We can roughly divide the commands into two classes: action commands and modeling commands. The modeling commands are used to define the model and the action commands tell MOSES what to do with the model. Normally, MOSES does its work quietly and does not inform you of anything. At any time, you can ask MOSES to report the situation of the system with a simple command. Consider for a moment an assistant that works for you, and suppose that one of the jobs of the assistant is to bring you coffee. In the beginning, you must tell the assistant not only to bring the coffee, but how much cream and sugar you want in it. If the assistant did not learn, you would soon tire of asking for coffee because of the explanation required. Fortunately, people learn - MOSES can also be taught. There are two "special" commands in MOSES that allow you to create something called a macro, which is simply a collection of commands. Carrying the above analogy a bit further, you can combine the instructions: get coffee, light cream, heavy sugar, into a single command - coffee. If you like conversation with your coffee, you can even add commands to "talk about sports" to the macro, but without special instruction, MOSES, the dutiful servant, will simple leave the coffee and walk silently away.