Writes to the standard error stream. You may find this useful when you want to pipe (search the internet for "pipe output") the output of a program to a file and still have the error messages appear on the console window.
The STDOUT/STDIN/STDERR commands are really only useful for making a console program. See the menu Project/Options.
name$ = STDIN$()
STDERR "This is sent to STDERR : "+name$ + "\n"