More Observations about Command Lines Skip these on first reading if you like. It is possible to put multiple commands on one line of text if the commands are separated by semicolons. Tcl works with lists a lot. The first element of this list is the command name and subsequent elements are the arguments. When using Tcl interactively, if a command requires arguments, you can execute a command without any arguments to see a short explanation of how it should be used.
Some commands are really families of actions where the action is determined by the first argument.
If you invoke such a command with an inappropriate first argument, you will get a list of the possibilities.