f << endl -- ends the line currently being put out to the file f.
It is an essential portable programming practice to use endl always, for writing newline characters (see newline) to a file will not terminate a line containing nets properly, and it will not flush the output buffer.
Ways to use endl:
Manipulator Database -- see Manipulator -- the class of all file manipulators
Manipulator File -- see Manipulator -- the class of all file manipulators
Manipulator Nothing -- see Manipulator -- the class of all file manipulators
new Manipulator from Function -- see Manipulator -- the class of all file manipulators
methods(Manipulator) -- see methods -- list methods
Manipulator NetFile -- see NetFile -- the class of all net files
NetFile << Manipulator -- see NetFile -- the class of all net files