KLH@MIT-AI 09/02/76 12:27:03
To: DLW at MIT-AI, ED at MIT-AI, RMS at MIT-AI, MOON at MIT-AI
CC: KLH at MIT-AI
Do you think you'd like to do a little work on the
reminder user interface?  I can get the mailer up, but I don't know
how long it would take to cons together an acceptable way of
specifying times etc... 
Let me describe how the current implementation is set up.
It's fairly ambitious and isn't debugged (there, there)
but is straightforward in concept.
	A message can have a "reminder expiration date" or
"reminder count", but NOT both - these are the same attribute,
distinguished by the LH being 0 for a reminder count.  When
the count runs out, or the next sending date/time is past the
expiration date, the message gets flushed.
	There can be any number of "reminder specs" which
actually define when to send the reminder.  Each spec can
have 2 components; the first (optional) specifies a "base"
date/time upon which the next component becomes active.  If
none exists, the current time is used as base.  The second
component can be either a date/time spec or an increment.
If an increment, its value is in minutes.  After the reminder
is sent, this will be added to current (or base) time to
get next sending time.  Since this is a full word, this
allows you to specify whichever aeon you prefer.
A date/time spec has 5 fields: year, month, day, hour, minute.
The reminder is sent at the specified date and time.
Any or all of the first 3 can be "Wild", as indicated by a zero
value in that field; the reminder then gets sent whenever
the time matches.
	The idea of having multiple reminder specs is that
their union forms the complete sending specification for that
message; whichever reminder spec comes soonest sets the time
for next sending.
	Structural diagram: (!?)

TERMINATION-SPEC::= Exp-Count|Exp-Date
	Exp-Count: reminder flushed after being sent this many times,
		irrespective of when, how often, etc.
	Exp-date: reminder flushed when next projected sending time is
		past this.

REMIND-SPEC::= timespec | timespec&timebase
	Timebase: Date & time after which this remind-spec becomes "active".
	Timespec: Increment|datetime
		Increment: Increment in minutes to add for next sending time.
		Datetime: 5-field date + time, reminder sent whenever
			it comes to pass... year, month, & day can all be WILD.
REMIND-SPEC
,
,
REMIND-SPEC
moksc;remind spec