From the NannyMUD documentation

LAST CHANGE

2000-12-09

FUNCTION

NAME
        ed - Edit a file.


SYNTAX
	void ed(void|string path, void|string exit_func)

DESCRIPTION
	With this function an interactive object (a player) can edit
	a file with the given path. If no `path' is given, the file
	of your's that last had an error in it is taken. `exit_func' 
	is called on completion	of the command.


NOTE
	This function is subject to the rules given by the functions
	`valid_read()' and `valid_write()'.