Programmer Guide/Concepts/Argument Passing

Many macros use the call-format: name command arguments (e.g. MSGBOX MSG text). If you want to pass quoted arguments to such a macro, use the format MSGBOX 'MSG text' instead of MSGBOX MSG 'text'. This is necessary because the argument string MSG 'text' is passed (after command-line processing) as MSGtext to the macro.If a new shell is called to run a macro, the id (8 hex digits) is assigned to the variable #SHELL of the caller. In the new shell, the variable SHELL is set to 'this_shellid caller_shellid'. The two variables can be used to identify the shells in communication messages.It is not necessary to use the command MACRO explicitly, because the interpreter tries to execute all 'non-shell' commands as a macro. This means the command line MACRO macroname is equivalent to command line macroname.

See also Definition of Macros.