This command marks the end of the IF..END IF SuperBASIC structure, and has no meaning on its own.
When the interpreter finds an IF condition statement it then evaluates the condition and carries out certain commands depending on whether the condition was true or false.
Having carried out those commands, the interpreter then looks for a related END IF command, and will pass control onto the statement following END IF.
This does however mean, that except under SMS, unless an in-line IF structure is being used, if this command is missing, the interpreter will carry on searching through the program and may just stop without an error if END IF does not appear anywhere in the program.
END IF need not appear in an in-line IF statement.
All ROMs (except for Minerva v1.93+ or SMS) can get mixed up with multiple in-line IF..END IF structures - see IF.
Checks are made on a program before it is run, and so if an END IF statement appears without a corresponding IF command, the error ‘Misplaced END IF’ is reported.