Success: set_flag(gc,verbose). set_flag(syntax_option, no_blanks). set_flag(syntax_option, not nl_in_quotes). % The following example will set a new library path [eclipse]: get_flag(library_path,Path), set_flag(library_path, ["/home/myuser/mylibs" | Path]). Path = ["/usr/local/ECLIPSE/lib"] yes. Fail: set_flag(statistics, some). Error: set_flag(X,a). (Error 4) set_flag("a",x). (Error 5) set_flag(blah, a). (Error 6) set_flag(gc,fred). (Error 6) set_flag(version,1). (Error 30)