Give an example of the use of temporal separation for security in a computing environment

What will be an ideal response?

In
some
secure
systems,
only
processes
of
one
sensitivity
level
are
run
at
one
time.
When
a
batch
of
tasks
requiring
higher
or
lower
security
are
to
be
run,
all
tasks
are
removed
from
the
system,
storage
media
containing
sensitive
data
and
programs
are
removed
and
new
ones
installed,
and
the
operating
system
is
rebooted.