** Future events
(Scheduling an eclipse; Totality)
To schedule an eclipse of the sun, which involves a number of related events.

First we define the events, and then we create a phrase to schedule them:

	{*}"Totality"

	At the time when the penumbra appears:
		say "The sunlight dies away to an eerie, brownish penumbra."

	At the time when the eclipse begins:
		say "The moon passes across the disc of the sun, plunging the world into darkness.";
		now the Chamber is dark.

	At the time when the eclipse ends:
		say "The moon passes away from the sun, and a gloomy penumbral light returns.";
		now the Chamber is lighted.
		
	At the time when normal sunlight returns:
		say "The sun shines once more bright in the sky, not to be eclipsed again on this spot for another thirty-seven years."

	To schedule an eclipse for (totality - a time):
		the penumbra appears at two minutes before totality;
		the eclipse begins at totality;
		the eclipse ends at three minutes after totality;
		normal sunlight returns at five minutes after totality.

Now we make use of the new phrase:
	
	{**}When play begins, schedule an eclipse for 3:27 PM.
	
	The Chamber is a room.  
	
	The time of day is 3:25 PM.
		
	Test me with "z / z / z / z / z / z / z / z / z".

We shall see much more about creating phrases later. Their advantage is that they enable a complicated sequence of operations to be given a meaningful name, and that they can be re-used many times as needed.