Requires that the group of commands that follow is to be treated
as a single unit. That is, the group of commands run as a result of
a single IF command. The END command ends the set of commands. A command
following a DO must begin on a new line.
END
Specifies the end of a set of commands initiated by the nearest
unended DO. END must be on a line by itself.
Restriction: Do
not use continuation characters in the DO-END sequence; they are taken
as a null command or cause unpredictable results.