setenv command

    (A) Function
        Defining an environment macro. 

    (B) Format

        setenv <name> [ <string> ]

    (C) Parameter
       <name>
           Designate an environment macro name.
       <string>
           Designate a macro definition character string.
           If <string> is not specified, the macro name is 
           interpreted as being undefined. 

    (D) Notes
        TIME, POSIT and MARKER are reservation environment macro names 
        defined by SECONDS. 
        When SECONDS starts up, a macro definition character string of 
        an environment macro whose name is the same as an environment 
        variable name in a SECONDS process is in advance defined in the 
        contents of the environment variable.  
        If a script macro that has the same name as another macro is 
        defined, the script macro is given preference over the macro. 
        An undefined macro name has a macro expansion under the condition
        of its macro definition character string being null. 

    (E) Related items
       listen command
       eval command
       define command