Calendar Mode and the Diary
===========================

Emacs provides the functions of a desk calendar, with a diary of past or planned events.  Display the calendar by typing M-x calendar. This command creates a window containing a three-month calendar centered on the current month, with point on the current date.  Or, provide a prefix argument by typing C-u M-x calendar; then you are prompted for the month and year to be the center of the three-month calendar.  In either case, you are now in Calendar mode.

Calendar mode makes it easy to look at the holidays or diary entries associated with various dates, and to change the diary entries.  You can move freely between the Calendar window and other windows.  To exit the calendar, type q.

Movement in the Calendar
------------------------

Calendar mode lets you move in logical units of time such as days, weeks, months, and years.  Sometimes you need to move to a specific date in order to enter commands affecting its display or the associated diary entries.  If you move outside the three months originally displayed, the calendar display scrolls automatically through time.

Motion by Integral Days, Weeks, Months, Years
.............................................

The commands for movement in the calendar buffer parallel the commands for movement in text.  You can move forward and backward by days, weeks, months, and years.

C-f
     Move point one day forward (calendar-forward-day).

C-b
     Move point one day backward (calendar-backward-day).

C-n
     Move point one week forward (calendar-forward-week).

C-p
     Move point one week backward (calendar-backward-week).

M-}
     Move point one month forward (calendar-forward-month).

M-{
     Move point one month backward (calendar-backward-month).

C-x ]
     Move point one year forward (calendar-forward-year).

C-x [
     Move point one year backward (calendar-forward-year).

The day and week commands are natural analogues of the usual Emacs commands for moving by characters and by lines.  Just as C-n usually moves to the same column in the following line, in Calendar mode it moves to the same day in the following week.  And C-p moves to the same day in the previous week.

The commands for motion by months and years work like those for weeks, but move a larger distance.  The month commands M-} and M-{ move forward or backward by an entire month's time.  The year commands C-x ] and C-x [ move forward or backward a whole year.

The easiest way to remember these commands is to consider months and years analogous to paragraphs and pages of text, respectively.  But the commands themselves are not quite analogous.  The ordinary Emacs paragraph commands move to the beginning or end of a paragraph, whereas these month and year commands move by an entire month or an entire year, which usually involves skipping across the end of a month or year.

Each of these commands accepts a numeric argument as a repeat count.  For convenience, the digit keys and the minus sign are bound in Calendar mode so that it is unnecessary to type the M- prefix.  For example, 100 C-f moves point 100 days forward from its present location.

Beginning or End of Week, Month or Year
.......................................

A week (or month, or year) is not just a quantity of days; we think of new weeks (months, years) as starting on particular days.  So Calendar mode provides commands to move to the beginning or end of the week, month or year:

C-a
     Move point to beginning of week (calendar-beginning-of-week).

C-e
     Move point to end of week (calendar-end-of-week).

M-a
     Move point to beginning of month (calendar-beginning-of-month).

M-e
     Move point to end of month (calendar-end-of-month).

M-<
     Move point to beginning of year (calendar-beginning-of-year).

M->
     Move point to end of year (calendar-end-of-year).

These commands also take numeric arguments as repeat counts, with the repeat count indicating how many weeks, months, or years to move backward or forward.

Particular Dates
................

Calendar mode provides some commands for getting to a particular date quickly.

g d
     Move point to specified date (calendar-goto-date).

o
     Center calendar around specified month (calendar-other-month).

.
     Move point to today's date (calendar-current-month).

g d (calendar-goto-date) prompts for a year, a month, and a day of the month, and then goes to that date.  Because the calendar includes all dates from the beginning of the current era, you must type the year in its entirety; that is, type 1990, not 90.

o (calendar-other-month) prompts for a month and year, then centers the three-month calendar around that month.

You can return to the current date with . (calendar-current-month).

Scrolling the Calendar through Time
-----------------------------------

The calendar display scrolls automatically through time when you move out of the visible portion.  You can also scroll it manually.  Imagine that the calendar window contains a long strip of paper with the months on it. Scrolling it means moving the strip so that new months become visible in the window.

C-x <
     Scroll calendar one month forward (scroll-calendar-left).

C-x >
     Scroll calendar one month backward (scroll-calendar-right).

C-v
     Scroll calendar three months forward (scroll-calendar-left-three-months).

M-v
     Scroll calendar three months backward (scroll-calendar-right-three-months).

The most basic calendar scroll commands scroll by one month at a time.  This means that there are two months of overlap between the display before the command and the display after.  C-x < scrolls the calendar contents one month to the left; that is, it moves the display forward in time.  C-x > scrolls the contents to the right, which moves backwards in time.

The commands C-v and M-v scroll the calendar by an entire ``screenful''---three months---in analogy with the usual meaning of these commands.  C-v makes later dates visible and M-v makes earlier dates visible.  These commands also take a numeric argument as a repeat count; in particular, since C-u (universal-argument) multiplies the next command by four, typing C-u C-v scrolls the calendar forward by a year and typing C-u M-v scrolls the calendar backward by a year.

Any of the special Calendar mode commands scrolls the calendar automatically as necessary to ensure that the date you have moved to is visible.

The Mark and the Region
-----------------------

The concept of the mark applies to the calendar just as to any other buffer, but it marks a date, not a position in the buffer. The region consists of the days between the mark and point (including the starting and stopping dates).

C-SPC
     Set the mark to today's date (calendar-set-mark).

C-@
     The same.

C-x C-x
     Interchange mark and point (calendar-exchange-point-and-mark).

M-=
     Display the number of days in the current region (calendar-count-days-region).

You set the mark in the calendar, as in any other buffer, by using C-@ or C-SPC (calendar-set-mark).  You return to the marked date with the command C-x C-x (calendar-exchange-point-and-mark) which puts the mark where point was and point where mark was.  The calendar is scrolled as necessary, if the marked date was not visible on the screen.  This does not change the extent of the region.

To determine the number of days in the region, type M-= (calendar-count-days-region).  The numbers of days printed is inclusive, that is, includes the days specified by mark and point.

The main use of the mark in the calendar is to remember dates that you may want to go back to.  To make this feature more useful, the mark ring (see Mark Ring) operates exactly as in other buffers:  Emacs remembers 16 previous locations of the mark.  To return to a marked date, type C-u C-SPC (or C-u C-@); this is the command calendar-set-mark given a numeric argument.  It moves point to where the mark was, restores the mark from the ring of former marks, and stores the previous point at the end of the mark ring.  So, repeated use of this command moves point through all the old marks on the ring, one by one.

Miscellaneous Calendar Commands
-------------------------------

p d
     Display day-in-year (calendar-print-day-of-year).

?
     Briefly describe calendar commands (describe-calendar-mode).

SPC
     Scroll the next window (scroll-other-window).

C-c C-l
     Regenerate the calendar window (redraw-calendar).

q
     Exit from calendar (exit-calendar).

If you want to know how many days have elapsed since the start of the year, or the number of days remaining in the year, type the p d command (calendar-print-day-of-year).  This displays both of those numbers in the echo area.

To display a brief description of the calendar commands, type ? (describe-calendar-mode).  For a fuller description, type C-h m.

You can use SPC (scroll-other-window) to scroll the other window.  This is handy when you display a list of holidays or diary entries in another window.

If the calendar window gets corrupted, type C-c C-l (redraw-calendar) to redraw it.

To exit from the calendar, type q (exit-calendar).  This buries all buffers related to the calendar and returns the window display to what it was when you entered the calendar.

Holidays
--------

The Emacs calendar knows about all major and many minor holidays.

h
     Display holidays for the date indicated by point (calendar-cursor-holidays).

x
     Mark holidays in the calendar window (mark-calendar-holidays).

u
     Unmark calendar window (calendar-unmark).

a
     List all holidays for the displayed three months in another window (list-calendar-holidays).

M-x holidays
     List all holidays for three months around today's date in another window.

To see if any holidays fall on a given date, position point on that date in the calendar window and use the h command.  The holidays are usually listed in the echo area, but if there are too many to fit in one line, then they are displayed in a separate window.

To find the distribution of holidays for a wider period, you can use the x command.  This places a * next to every date on which a holiday falls.  The command applies both to the currently visible dates and to new dates that become visible by scrolling.  To turn marking off and erase the current marks, type u, which also erases any diary marks (see Diary).

To get even more detailed information, use the a command, which displays a separate buffer containing a list of all holidays in the current three-month range.

You can display the list of holidays for the current month and the preceding and succeeding months even if you don't have a calendar window.  Use the command M-x holidays.  If you want the list of holidays centered around a different month, use C-u M-x holidays and type the month and year.

The holidays known to Emacs include American holidays and the major Christian, Jewish, and Islamic holidays; when floating point is available, Emacs also knows about solstices and equinoxes.  The dates used by Emacs for holidays are based on current practice, not historical fact. Historically, for instance, the start of daylight savings time and even its existence have varied from year to year.  However present American law mandates that daylight savings time begins on the first Sunday in April; this is the definition that Emacs uses, even though it is wrong for some prior years.

Times of Sunrise and Sunset
---------------------------

Emacs can tell you, to within a minute or two, the times of sunrise and sunset for any date, if floating point is available.

S
     Display times of sunrise and sunset for the date indicated by point (calendar-sunrise-sunset).

M-x sunrise-sunset
     Display times of sunrise and sunset for today's date.

Move point to the date you want, and type S, to display the local times of sunrise and sunset in the echo area.

You can display the times of sunrise and sunset for the current date even if you don't have a calendar window.  Use the command M-x sunrise-sunset.  If you want the times of sunrise and sunset for a different date, use C-u M-x sunrise-sunset and type the year, month, and day.

Because the times of sunrise and sunset depend on the location on earth, you need to tell Emacs your latitude, longitude, and location name.  Here is an example of what to set:

     (setq calendar-latitude 40.1)
     (setq calendar-longitude -88.2)
     (setq calendar-location-name "Urbana, IL")

Use one decimal place in the values of calendar-latitude and calendar-longitude.

Your time zone also affects the local time of sunrise and sunset. Emacs usually gets this information from the operating system, but if these values are not what you want (or if the operating system does not supply them), you'll need to set them yourself, like this:

     (setq calendar-time-zone -360)
     (setq calendar-standard-time-zone-name "CST")
     (setq calendar-daylight-time-zone-name "CDT")

The value of calendar-time-zone is the number of minutes difference between your local standard time and Universal Time (Greenwich time).  The values of calendar-standard-time-zone-name and calendar-daylight-time-zone-name are the abbreviations used in your time zone.

Emacs displays the times of sunrise and sunset corrected for daylight savings time (this convenience is unusual; most tables of sunrise and sunset use standard time).  The default rule for the starting and stopping dates of daylight savings time is the American rule.  See Daylight Savings

You can display the times of sunrise and sunset for any location and any date with C-u C-u M-x sunrise-sunset.  Emacs asks you for a longitude, latitude, number of minutes difference from Universal time, and date, and then tells you the times of sunrise and sunset for that location on that date.  The times are usually given in the echo area, but if the message is too long fit in one line, they are displayed in a separate window.

Phases of the Moon
------------------

Emacs can tell you the dates and times of the phases of the moon (new moon, first quarter, full moon, last quarter), if floating point is available.

M
     List, in another window, the dates and times for all the quarters of the moon for the three-month period shown in the calendar window (calendar-phases-of-moon).

M-x phases-of-moon
     List dates and times of the quarters of the moon for three months around today's date in another window.

Use the M command to display a separate buffer of the phases of the moon for the current three-month range.  The dates and times listed are accurate to within a few minutes.

You can display the list of the phases of the moon for the current month and the preceding and succeeding months even if you don't have a calendar window.  Use the command M-x phases-of-moon.  If you want the phases of the moon centered around a different month, use C-u M-x phases-of-moon and type the month and year.

The dates and times given for the phases of the moon are given in local time (corrected for daylight savings, when appropriate); but if the variable calendar-time-zone is void, Universal Time (the Greenwich time zone) is used.  See Daylight Savings

Our Calendar and Other Calendars
--------------------------------

The Emacs calendar displayed is always the Gregorian calendar, sometimes called the ``new style'' calendar, which is used in most of the world today.  However, this calendar did not exist before the sixteenth century and was not widely used before the eighteenth century; it did not fully displace the Julian calendar and gain universal acceptance until the early twentieth century.  This poses a problem for the Emacs calendar: you can ask for the calendar of any month starting with January, year 1 of the current era, but the calendar displayed is the Gregorian, even for a date at which the Gregorian calendar did not exist!

Emacs knows about several different calendars, though, not just the Gregorian calendar.  The following commands describe the date indicated by point in various calendar notations:

p c
     Display ISO commercial calendar equivalent for selected day (calendar-print-iso-date).

p j
     Display Julian date for selected day (calendar-print-julian-date).

p a
     Display astronomical (Julian) day number for selected day (calendar-print-astro-day-number).

p h
     Display Hebrew date for selected day (calendar-print-hebrew-date).

p i
     Display Islamic date for selected day (calendar-print-islamic-date).

p f
     Display French Revolutionary date for selected day (calendar-print-french-date).

p m
     Display Mayan date for selected day (calendar-print-mayan-date).

If you are interested in these calendars, you can convert dates one at a time.  Put point on the desired date of the Gregorian calendar and press the appropriate keys.  The p is a mnemonic for ``print'' since Emacs ``prints' the equivalent date in the echo area.

The ISO commercial calendar is used largely in Europe.

The Julian calendar, named after Julius Caesar, was the one used in Europe throughout medieval times, and in many countries up until the nineteenth century.

Astronomers use a simple counting of days elapsed since noon, Monday, January 1, 4713 B.C. on the Julian calendar.  The number of days elapsed is called the Julian day number or the Astronomical day number.

The Hebrew calendar is the one used to determine the dates of Jewish holidays.  Hebrew calendar dates begin and end at sunset.

The Islamic (Moslem) calendar is the one used to determine the dates of Moslem holidays.  There is no universal agreement in the Islamic world about the calendar; Emacs uses a widely accepted version, but the precise dates of Islamic holidays often depend on proclamation by religious authorities, not on calculations.  As a consequence, the actual dates of occurrence can vary slightly from the dates computed by Emacs.  Islamic calendar dates begin and end at sunset.

The French Revolutionary calendar was created by the Jacobins after the 1789 revolution, to represent a more secular and nature-based view of the annual cycle, and to install a 10-day week in a rationalization measure similar to the metric system.  The French government officially abandoned this calendar at the end of 1805.

The Maya of Central America used three separate, overlapping calendar systems, the long count, the tzolkin, and the haab. Emacs knows about all three of these calendars.  Experts dispute the exact correlation between the Mayan calendar and our calendar; Emacs uses the Goodman-Martinez-Thompson correlation in its calculations.

You can move to dates that you specify on the Commercial, Julian, astronomical, Hebrew, Islamic, or French calendars:

g c
     Move point to a date specified by the ISO commercial calendar (calendar-goto-iso-date).

g j
     Move point to a date specified by the Julian calendar (calendar-goto-julian-date).

g a
     Move point to a date specified by astronomical (Julian) day number (calendar-goto-astro-day-number).

g h
     Move point to a date specified by the Hebrew calendar (calendar-goto-hebrew-date).

g i
     Move point to a date specified by the Islamic calendar (calendar-goto-islamic-date).

g f
     Move point to a date specified by the French Revolutionary calendar (calendar-goto-french-date).

These commands ask you for a date on the other calendar, move point to the Gregorian calendar date equivalent to that date, and display the other calendar's date in the echo area.  Emacs uses strict completion (see Completion) whenever it asks you to type a month name, so you don't have to worry about the spelling of Hebrew, Islamic, or French names.

One common question concerning the Hebrew calendar is the computation of the anniversary of a date of death, called a ``yahrzeit.''  The Emacs calendar includes a facility for such calculations.  If you are in the calendar, the command M-x list-yahrzeit-dates asks you for a range of years and then displays a list of the yahrzeit dates for those years for the date given by point.  If you are not in the calendar, this command first asks you for the date of death and the range of years, and then displays the list of yahrzeit dates.

Emacs also has many commands for movement on the Mayan calendars.

g m l
     Move point to a date specified by the Mayan long count calendar (calendar-goto-mayan-long-count-date).

g m p t
     Move point to the previous occurrence of a date specified by the Mayan tzolkin calendar (calendar-previous-tzolkin-date).

g m n t
     Move point to the next occurrence of a date specified by the Mayan tzolkin calendar (calendar-next-tzolkin-date).

g m p h
     Move point to the previous occurrence of a date specified by the Mayan haab calendar (calendar-previous-haab-date).

g m n h
     Move point to the next occurrence of a date specified by the Mayan haab calendar (calendar-next-haab-date).

g m p c
     Move point to the previous occurrence of a date specified by the Mayan calendar round (calendar-previous-calendar-round-date).

g m n c
     Move point to the next occurrence of a date specified by the Mayan calendar round (calendar-next-calendar-round-date).

To understand these commands, you need to understand the Mayan calendars. The long count is a counting of days with units

1 kin
     = 1  day

1 uinal
     = 20 kin

1 tun
     = 18 uinal

1 katun
     = 20 tun

1 baktun
     = 20 katun

Thus, the long count date 12.16.11.16.6 means 12 baktun, 16 katun, 11 tun, 16 uinal, and 6 kin.  The Emacs calendar can handle Mayan long count dates as early as 7.17.18.13.1, but no earlier.  When you use the g m l command, type the Mayan long count date with the baktun, katun, tun, uinal, and kin separated by periods.

The Mayan tzolkin calendar is a cycle of 260 days formed by a pair of independent cycles of 13 and 20 days.  Like the haab cycle, this cycle repeats endlessly, and you can go backward and forward to the previous or next (respectively) point in the cycle.  When you type g m p t, Emacs asks you for a tzolkin date and moves point to the previous occurrence of that date; type g m n t to go to the next occurrence.

The Mayan haab calendar is a cycle of 365 days arranged as 18 months of 20 days each, followed a 5-day monthless period.  Since this cycle repeats endlessly, Emacs lets you go backward and forward to the previous or next (respectively) point in the cycle.  Type g m p h to go to the previous haab date; Emacs asks you for a haab date and moves point to the previous occurrence of that date.  Similarly, type g m n h to go to the next haab date.

The Maya also used the combination of the tzolkin date and the haab date.  This combination is a cycle of about 52 years called a calendar round.  If you type g m p c, Emacs asks you for both a haab and a tzolkin date and then moves point to the previous occurrence of that combination.  Use g m p c to move point to the next occurrence.  Emacs signals an error if the haab/tzolkin date you have typed cannot occur.

Emacs uses strict completion (see Completion) whenever it asks you to type a Mayan name, so you don't have to worry about spelling.

The Diary
---------

Associated with the Emacs calendar is a diary that keeps track of appointments or other events on a daily basis.  To use the diary feature, you must first create a diary file containing a list of events and their dates.  Then Emacs can automatically pick out and display the events for today, for the immediate future, or for any specified date.

By default, Emacs expects your diary file to be named ~/diary. It uses the same format as the calendar utility.  A sample ~/diary file is:

     12/22/1988 Twentieth wedding anniversary!!
     &1/1. Happy New Year!
     10/22 Ruth's birthday.
     * 21, *: Payday
     Tuesday--weekly meeting with grad students at 10am
              Supowit, Shen, Bitner, and Kapoor to attend.
     1/13/89 Friday the thirteenth!!
     &thu 4pm squash game with Lloyd.
     mar 16 Dad's birthday
     April 15, 1989 Income tax due.
     &* 15 time cards due.

Although you probably will start by creating a diary manually, Emacs provides a number of commands to let you view, add, and change diary entries.  You can also share diary entries with other users (see Included Diary Files).

Commands Displaying Diary Entries
---------------------------------

Once you have created a ~/diary file, you can view it within Calendar mode.  You can also view today's events independently of Calendar mode.

d
     Display any diary entries for the selected date (view-diary-entries).

s
     Display entire diary file (show-all-diary-entries).

m
     Mark all visible dates that have diary entries (mark-diary-entries).

u
     Unmark calendar window (calendar-unmark).

M-x print-diary-entries
     Print a hard copy of the diary display as it appears.

M-x diary
     Display any diary entries for today's date.

Displaying the diary entries with d shows in a separate window the diary entries for the date indicated by point in the calendar window.  The mode line of the new window shows the date of the diary entries and any holidays that fall on that date.

If you specify a numeric argument with d, then all the diary entries for that many successive days are shown.  Thus, 2 d displays all the entries for the selected date and for the following day.

To get a broader overview of which days are mentioned in the diary, use the m command to mark those days in the calendar window.  The marks appear next to the dates to which they apply.  The m command affects the dates currently visible and, if you scroll the calendar, newly visible dates as well.  The u command deletes all diary marks (and all holiday marks too; see Holidays), not only in the dates currently visible, but dates that become visible when you scroll the calendar.

For more detailed information, use the s command, which displays the entire diary file.

Display of selected diary entries uses the selective display feature, the same feature that Outline mode uses to show part of an outline (see Outline Mode).  This involves hiding the diary entries that are not relevant, by changing the preceding newline into an ASCII control-m (code 015).  The hidden lines are part of the buffer's text, but they are invisible; they don't appear on the screen.  When you save the diary file, the control-m characters are saved as newlines; thus, the invisible lines become ordinary lines in the file.

Because the diary buffer as you see it is an illusion, simply printing the contents does not print what you see on your screen.  So there is a special command to print a hard copy of the buffer as it appears; this command is M-x print-diary-entries.  It sends the data directly to the printer.  You can customize it like lpr-region (see Hardcopy).

The command M-x diary displays the diary entries for the current date, independently of the calendar display, and optionally for the next few days as well; the variable number-of-diary-entries specifies how many days to include (see Customization).

If you put in your .emacs file:

     (diary)

it automatically displays a window with the day's diary entries, when you enter Emacs.  The mode line of the displayed window shows the date and any holidays that fall on that date.

The Diary File
--------------

Your diary file is a file that records events associated with particular dates.  The name of the diary file is specified by the variable diary-file; ~/diary is the default.  You can use the same file for the calendar utility program, since its formats are a subset of the ones allowed by the Emacs Calendar.

Each entry in the file describes one event and consists of one or more lines.  It always begins with a date specification at the left margin. The rest of the entry is simply text to describe the event.  If the entry has more than one line, then the lines after the first must begin with whitespace to indicate they continue a previous entry.

Here are some sample diary entries, illustrating different ways of formatting a date.  The examples all show dates in American order (month, day, year), but Calendar mode offers (day, month, year) ordering too.

     4/20/93  Switch-over to new tabulation system
     apr. 25  Start tabulating annual results
     4/30  Results for April are due
     */25  Monthly cycle finishes
     Friday  Don't leave without backing up files

The first entry appears only once, on April 20, 1993.  The second and third appear every year on the specified dates, and the fourth uses a wildcard (asterisk) for the month, so it appears on the 25th of every month.  The final entry appears every week on Friday.

You can also use just numbers to express a date, as in MONTH/DAY or MONTH/DAY/YEAR.  This must be followed by a nondigit.  In the date itself, MONTH and DAY are numbers of one or two digits.  YEAR is a number and may be abbreviated to the last two digits; that is, you can use 11/12/1989 or 11/12/89.

A date may be generic, or partially unspecified.  Then the entry applies to all dates that match the specification.  If the date does not contain a year, it is generic and applies to any year. Alternatively, MONTH, DAY, or YEAR can be a *; this matches any month, day, or year, respectively.  Thus, a diary entry 3/*/* matches any day in March of any year.

Dates can also have the form MONTHNAME DAY or MONTHNAME DAY, YEAR, where the month's name can be spelled in full or abbreviated to three characters (with or without a period).  Case is not significant.  If the date does not contain a year, it is generic and applies to any year.  Also, MONTHNAME, DAY, or YEAR can be a * which matches any month, day, or year, respectively.

If you prefer the European style of writing dates---in which the day comes before the month---type M-x european-calendar while in the calendar, or set the variable european-calendar-style to t in your .emacs file before the calendar or diary command. This mode interprets all dates in the diary in the European manner, and also uses European style for displaying diary dates.  (Note that there is no comma after the MONTHNAME in the European style.)

To revert to the (default) American style of writing dates, type M-x american-calendar.

You can use the name of a day of the week as a generic date which applies to any date falling on that day of the week.  You can abbreviate the day of the week to three letters (with or without a period) or spell it in full; it need not be capitalized.

You can inhibit the marking of certain diary entries in the calendar window; to do this, insert an ampersand (&) at the beginning of the entry, before the date.  This has no effect on display of the entry in the diary window; it affects only marks on dates in the calendar window.  Nonmarking entries are especially useful for generic entries that would otherwise mark many different dates.

Lines that do not begin with valid dates and do not continue a preceding entry are ignored.

If the first line of a diary entry consists only of the date or day name with no following blanks or punctuation, then the diary window display doesn't include that line; only the continuation lines appear. For example:

     02/11/1989
           Bill B. visits Princeton today
           2pm Cognitive Studies Committee meeting
           2:30-5:30 Liz at Lawrenceville
           4:00pm Dentist appt
           7:30pm Dinner at George's
           8:00-10:00pm concert

appears in the diary window without the date line at the beginning. This style of entry looks neater when you display just a single day's entries, but can cause confusion if you ask for more than one day's entries.

You can edit the diary entries as they appear in the window, but it is important to remember that the buffer displayed contains the entire diary file, with portions of it concealed from view.  This means, for instance, that the C-f (forward-char) command can put point at what appears to be the end of the line, but what is in reality the middle of some concealed line.  Be careful when editing the diary entries!  Inserting additional lines or adding/deleting characters in the middle of a visible line cannot cause problems.  Watch out for C-e (end-of-line), however; it may put you at the end of a concealed line far from where point appears to be!  Before editing the diary, it is best to display the entire file with s (show-all-diary-entries).

While in the calendar, there are several commands to help you in making entries to your diary.

i d
     Add a diary entry for the selected date (insert-diary-entry).

i w
     Add a diary entry for the selected day of the week (insert-weekly-diary-entry).

i m
     Add a diary entry for the selected day of the month (insert-monthly-diary-entry).

i y
     Add a diary entry for the selected day of the year (insert-yearly-diary-entry).

You can make a diary entry for a specific date by moving point to that date in the calendar window and using the i d command.  This command displays the end of your diary file in another window and inserts the date; you can then type the rest of the diary entry.

If you want to make a diary entry that applies to a specific day of the week, move point to that day of the week (any occurrence will do) and use the i w command.  This displays the end of your diary file in another window and inserts the day-of-week as a generic date; you can then type the rest of the diary entry.

You make a monthly diary entry in the same fashion.  Move point to the day of the month, use the i m command, and type the diary entry. Similarly, you make a yearly diary entry with the i y command.

All of the above commands make marking diary entries.  If you want the diary entry to be nonmarking, give a prefix argument to the command.  For example, C-u i w makes a nonmarking, weekly diary entry.

If you modify the diary, be sure to write the file before exiting from the calendar.

Special Diary Entries
---------------------

In addition to entries based on calendar dates, your diary file can contain entries for regularly occurring events such as anniversaries.  These entries are based on expressions (sexps) that Emacs evaluates as it scans the diary file.  Such an entry is indicated by %% at the beginning (preceded by & for a nonmarking entry), followed by a sexp in parentheses.  Calendar mode offers commands to make it easier to put some of these special entries in your diary.

i a
     Add an anniversary diary entry for the selected date (insert-anniversary-diary-entry).

i b
     Add a block diary entry for the current region (insert-block-diary-entry).

i c
     Add a cyclic diary entry starting at the date (insert-cyclic-diary-entry).

If you want to make a diary entry that applies to the anniversary of a specific date, move point to that date and use the i a command. This displays the end of your diary file in another window and inserts the anniversary description; you can then type the rest of the diary entry.

The effect of i a is to add a diary-anniversary sexp to your diary file.  You can also add one manually, for instance:

     %%(diary-anniversary 10 31 1948) Arthur's birthday

This entry applies to October 31 in any year after 1948; 10 31 1948 specifies the date.  (If you are using the European calendar style, the month and day are interchanged.)  The reason this sexp requires a beginning year is that advanced diary functions can use it to calculate the number of elapsed years (see Sexp Diary Entries).

You can make a diary entry entry for a block of dates by setting the mark at the date at one end of the block, moving point to the date at the other end of the block, and using the i b command.  This command causes the end of your diary file to be displayed in another window and the block description to be inserted; you can then type the diary entry.

Here is such a diary entry that applies to all dates from June 24, 1990 through July 10, 1990:

     %%(diary-block 6 24 1990 7 10 1990) Vacation

The 6 24 1990 indicates the starting date and the 7 10 1990 indicates the stopping date.  (Again, if you are using the European calendar style, the month and day are interchanged.)

You can specify cyclic diary entries that repeat after a fixed interval of days.  Move point to the starting date and use the i c command.  After you specify the length of interval, this command displays the end of your diary file in another window and inserts the cyclic event description; you can then type the rest of the diary entry.

The sexp corresponding to the i c command looks like:

     %%(diary-cyclic 50 3 1 1990) Renew medication

which applies to March 1, 1990 and every 50th day following; 3 1 1990 specifies the starting date.  (If you are using the European calendar style, the month and day are interchanged.)

All three of the these commands make marking diary entries.  If you want the diary entry to be nonmarking, give a numeric argument to the command.  For example, C-u i a makes a nonmarking anniversary diary entry.

Marking sexp diary entries in the calendar is extremely time-consuming, since every date visible in the calendar window must be individually checked.  So it's a good idea to make sexp diary entries nonmarking with &.

One sophisticated kind of sexp, a floating diary entry, has no corresponding command.  The floating diary entry specifies a regularly-occurring event by offsets specified in days, weeks, and months.  It is comparable to a crontab entry interpreted by the cron utility on Unix systems.

Here is a nonmarking, floating diary entry that applies to the last Thursday in November:

     &%%(diary-float 11 4 -1) American Thanksgiving

The 11 specifies November (the eleventh month), the 4 specifies Thursday (the fourth day of the week, where Sunday is numbered zero), and the -1 specifies ``last'' (1 would mean ``first'', 2 would mean ``second'', -2 would mean ``second-to-last'', and so on).  The month can be a single month or a list of months.  Thus you could change the 11 above to '(1 2 3) and have the entry apply to the last Thursday of January, February, and March.  If the month is t, the entry applies to all months of the year.

The sexp feature of the diary allows you to specify diary entries based on any Emacs Lisp expression.  You can use the library of built-in functions or you can write your own functions.  The built-in functions include the ones shown in this section, plus a few others (see Sexp Diary Entries).

The generality of sexps lets you specify any diary entry that you can describe algorithmically.  Suppose you get paid on the 21st of the month if it is a weekday, and to the Friday before if the 21st is on a weekend.  The diary entry

     &%%(let ((dayname (calendar-day-of-week date))
              (day (car (cdr date))))
           (or (and (= day 21) (memq dayname '(1 2 3 4 5)))
               (and (memq day '(19 20)) (= dayname 5)))
              ) Pay check deposited

to just those dates.  This example illustrates how the sexp can depend on the variable date; this variable is a list (MONTH DAY YEAR) that gives the Gregorian date for which the diary entries are being found.  If the value of the sexp is t, the entry applies to that date.  If the sexp evaluates to nil, the entry does not apply to that date.

Customizing the Calendar and Diary
----------------------------------

There are many customizations that you can use to make the calendar and diary suit your personal tastes.

Customizing the Calendar
........................

If you set the variable view-diary-entries-initially to t, calling up the calendar automatically displays the diary entries for the current date as well.  The diary dates appear only if the current date is visible.  If you add both of the following lines to your .emacs file:

     (setq view-diary-entries-initially t)
     (calendar)

they display both the calendar and diary windows whenever you start Emacs.

Similarly, if you set the variable view-calendar-holidays-initially to t, entering the calendar automatically displays a list of holidays for the current three month period.  The holiday list appears in a separate window.

You can set the variable mark-diary-entries-in-calendar to t in order to place a plus sign (+) beside any dates with diary entries. Whenever the calendar window is displayed or redisplayed, the diary entries are automatically marked for holidays.

Similarly, setting the variable mark-holidays-in-calendar to t places an asterisk (*) after all holiday dates visible in the calendar window.

There are many customizations that you can make with the hooks provided.  For example, the variable calendar-load-hook, whose default value is nil, is a normal hook run when the calendar package is first loaded (before actually starting to display the calendar).

The variable initial-calendar-window-hook, whose default value is nil, is a normal hook run the first time the calendar window is displayed.  The function is invoked only when you first enter Calendar mode, not when you redisplay an existing Calendar window.  But if you leave the calendar with the q command and reenter it, the hook runs again.

The variable today-visible-calendar-hook, whose default value is nil, is a normal hook run after the calendar buffer has been prepared with the calendar when the current date is visible in the window.  One use of this hook is to replace today's date with asterisks; a function calendar-star-date is included for this purpose.  In your .emacs file, put:

     (setq today-visible-calendar-hook 'calendar-star-date)

Another standard hook function adds asterisks around the current date. Here's how to use it:

     (setq today-visible-calendar-hook 'calendar-mark-today)

A corresponding variable, today-invisible-calendar-hook, whose default value is nil, is a normal hook run after the calendar buffer text has been prepared, if the current date is not visible in the window.

Customizing the Holidays
........................

Emacs knows about holidays defined by entries on one of several lists. You can customize theses lists of holidays to your own needs, adding holidays or deleting lists of holidays.  The lists of holidays that Emacs uses are for general holidays (general-holidays), local holidays (local-holidays), Christian holidays (christian-holidays), Hebrew (Jewish) holidays (hebrew-holidays), Islamic (Moslem) holidays (islamic-holidays), and other holidays (other-holidays).

The general holidays are, by default, holidays common throughout the United States.  To eliminate these holidays, set general-holidays to nil.

There are no default local holidays (but sites may supply some).  You can set the variable local-holidays to any list of holidays, as described below.

By default, Emacs does not consider all the holidays of these religions, only those commonly found in secular calendars.  For a more extensive collection of religious holidays, you can set any (or all) of the variables all-christian-calendar-holidays, all-hebrew-calendar-holidays, or all-islamic-calendar-holidays to t.  If you want to eliminate the religious holidays, set any or all of the corresponding variables christian-holidays, hebrew-holidays, and islamic-holidays to nil.

You can set the variable other-holidays to any list of holidays.  This list, normally empty, is intended for your use.

Each of the lists (general-holidays, local-holidays, christian-holidays, hebrew-holidays, islamic-holidays, and other-holidays) is a list of holiday forms, each holiday form describing a holiday (or sometimes a list of holidays).  Holiday forms may have the following formats:

(holiday-fixed MONTH DAY STRING)
     A fixed date on the Gregorian calendar.  MONTH and DAY are numbers, STRING is the name of the holiday.

(holiday-float MONTH DAYNAME K STRING)
     The Kth DAYNAME in MONTH on the Gregorian calendar (DAYNAME=0 for Sunday, and so on); negative K means count back from the end of the month.  STRING is the name of the holiday.

(holiday-hebrew MONTH DAY STRING)
     A fixed date on the Hebrew calendar.  MONTH and DAY are numbers, STRING is the name of the holiday.

(holiday-islamic MONTH DAY STRING)
     A fixed date on the Islamic calendar.  MONTH and DAY are numbers, STRING is the name of the holiday.

(holiday-julian MONTH DAY STRING)
     A fixed date on the Julian calendar.  MONTH and DAY are numbers, STRING is the name of the holiday.

(holiday-sexp SEXP STRING)
     SEXP is a Lisp expression that should use the variable year to compute the date of a holiday, or nil if the holiday doesn't happen this year.  The value represents the date as a list of the form (MONTH DAY YEAR).  STRING is the name of the holiday.

(if BOOLEAN HOLIDAY-FORM &optional HOLIDAY-FORM)
     A choice between two holidays based on the value of BOOLEAN.

(FUNCTION &optional ARGS)
     Dates requiring special computation; ARGS, if any, are passed in a list to the function calendar-holiday-function-FUNCTION.

For example, suppose you want to add Bastille Day, celebrated in France on July 14.  You can do this by adding the following line to your .emacs file:

     (setq other-holidays '((holiday-fixed 7 14 "Bastille Day")))

The holiday form (holiday-fixed 7 14 "Bastille Day") specifies the fourteenth day of the seventh month (July).

Many holidays occur on a specific day of the week, at a specific time of month.  Here is a holiday form describing Hurricane Supplication Day, celebrated in the Virgin Islands on the fourth Monday in August:

     (holiday-float 8 1 4 "Hurricane Supplication Day")

Here the 8 specifies August, the 1 specifies Monday (Sunday is 0, Tuesday is 2, and so on), and the 4 specifies the fourth occurrence in the month (1 specifies the first occurrence, 2 the second occurrence, -1 the last occurrence, -2 the second-to-last occurrence, and so on).

You can specify holidays that occur on fixed days of the Hebrew, Islamic, and Julian calendars too.  For example,

     (setq other-holidays
           '((holiday-hebrew 10 2 "Last day of Hanukkah")
             (holiday-islamic 3 12 "Mohammed's Birthday")
             (holiday-julian 4 2 "Jefferson's Birthday")))

adds the last day of Hanukkah (since the Hebrew months are numbered with 1 starting from Nisan), the Islamic feast celebrating Mohammed's birthday (since the Islamic months are numbered from 1 starting with Muharram), and Thomas Jefferson's birthday, which is 2 April 1743 on the Julian calendar.

To include a holiday conditionally, use either the if or the sexp form.  For example, American presidential elections occur on the first Tuesday after the first Monday in November of years divisible by 4:

     (holiday-sexp (if (= 0 (% year 4))
                        (calendar-gregorian-from-absolute
                      (1+ (calendar-dayname-on-or-before
                            1 (+ 6 (calendar-absolute-from-gregorian
                                     (list 11 1 year))))))
                   "US Presidential Election"))

or

     (if (= 0 (% displayed-year 4))
         (fixed 11
                (extract-calendar-day
                  (calendar-gregorian-from-absolute
                    (1+ (calendar-dayname-on-or-before
                          1 (+ 6 (calendar-absolute-from-gregorian
                                   (list 11 1 displayed-year)))))))
                "US Presidential Election"))

Some holidays just don't fit into any of these forms because special calculations are involved in their determination.  In such cases you must write a Lisp function to do the calculation.  To include eclipses of the sun, for example, add (eclipses) to other-holidays and write an Emacs Lisp function eclipses that returns a (possibly empty) list of the relevant Gregorian dates among the range visible in the calendar window, with descriptive strings, like this:

     (((6 27 1991) "Lunar Eclipse") ((7 11 1991) "Solar Eclipse") ... )

Date Display Format
...................

You can customize the manner of displaying dates in the diary, in mode lines, and in messages by setting calendar-date-display-form.  This variable is a list of expressions that can involve the variables month, day, and year, all numbers in string form, and monthname and dayname, both alphabetic strings.  In the American style, the default value of this list is as follows:

     ((if dayname (concat dayname ", ")) monthname " " day ", " year)

while in the European style this value is the default:

     ((if dayname (concat dayname ", ")) day " " monthname " " year)

The ISO standard date representation is this:

     (year "-" month "-" day)

This specifies a typical American format:

     (month "/" day "/" (substring year -2))

Time Display Format
...................

In the calendar, diary, and related buffers, Emacs displays times of day in the conventional American style with the hours from 1 through 12, minutes, and either am or pm.  If you prefer the ``military'' (European) style of writing times---in which the hours go from 00 to 23---you can alter the variable calendar-time-display-form.  This variable is a list of expressions that can involve the variables 12-hours, 24-hours, and minutes, all numbers in string form, and am-pm and time-zone, both alphabetic strings.  The default definition of calendar-time-display-form is as follows:

     (12-hours ":" minutes am-pm
               (if time-zone " (") time-zone (if time-zone ")"))

Setting calendar-time-display-form to

     (24-hours ":" minutes
               (if time-zone " (") time-zone (if time-zone ")"))

gives military-style times like 21:07 (UT) if time zone names are defined, and times like 21:07 if they are not.

Daylight Savings Time
.....................

Emacs understands the difference between standard time and daylight savings time---the times given for sunrise, sunset, solstices, equinoxes, and the phases of the moon take that into account.  The rules for daylight savings time vary from place to place and have also varied historically from year to year.  To do the job properly, Emacs needs to know which rules to use.

Some operating systems keep track of the rules that apply to the place where you are; on these systems, Emacs gets the information it needs from the system automatically.  If some or all of this information is missing, Emacs fills in the gaps with the rules currently used in Cambridge, Massachusetts.  If the default choice of rules is not appropriate for your location, you can tell Emacs the rules to use by setting certain variables.

These variables are calendar-daylight-savings-starts and calendar-daylight-savings-ends.  Their values should be Lisp expressions that refer to the variable year, and evaluate to the Gregorian date on which daylight savings time starts or (respectively) ends, in the form of a list (MONTH DAY YEAR). The values should be nil if your area does not use daylight savings time.

Emacs uses these expressions to determine the starting date of daylight savings time for the holiday list and for correcting times of day in the solar and lunar calculations.

The values for Cambridge, Massachusetts are as follows:

     (calendar-nth-named-day 1 0 4 year)
     (calendar-nth-named-day -1 0 10 year)

i.e. the first 0th day (Sunday) of the fourth month (April) in the year specified by year, and the last Sunday of the tenth month (October) of that year.  If daylight savings time were changed to start on October 1, you would set calendar-daylight-savings-starts to this:

     (list 10 1 year)

For a more complex example, suppose daylight savings time begins on the first of Nisan on the Hebrew calendar.  You would set calendar-daylight-savings-starts as follows:

     (calendar-gregorian-from-absolute
       (calendar-absolute-from-hebrew
         (list 1 1 (+ year 3760))))

because Nisan is the first month in the Hebrew calendar and the Hebrew year differs from the Gregorian year by 3760 at Nisan.

If there is no daylight savings time at your location, or if you want all times in standard time, set calendar-daylight-savings-starts and calendar-daylight-savings-ends to nil.

This variable specifies the difference between daylight savings time and standard time, measured in minutes.  The value for Cambridge is 60.

These variables specify is the number of minutes after midnight local time when the transition to and from daylight savings time should occur.  For Cambridge, both variables' values are 120.

Customizing the Diary
.....................

Ordinarily, the mode line of the diary buffer window indicates any holidays that fall on the date of the diary entries.  The process of checking for holidays can take several seconds, so including holiday information delays the display of the diary buffer noticeably.  If you'd prefer to have a faster display of the diary buffer but without the holiday information, set the variable holidays-in-diary-buffer to nil.

The variable number-of-diary-entries controls the number of days of diary entries to be displayed at one time.  It affects the initial display when view-diary-entries-initially is t, as well as the command M-x diary.  For example, the default value is 1, which says to display only the current day's diary entries.  If the value is 2, both the current day's and the next day's entries are displayed.  The value can also be a vector of seven elements: if the value is [0 2 2 2 2 4 1] then no diary entries appear on Sunday, the current date's and the next day's diary entries appear Monday through Thursday, Friday through Monday's entries appear on Friday, while on Saturday only that day's entries appear.

The variable print-diary-entries-hook is a normal hook run after preparation of a temporary buffer containing just the diary entries currently visible in the diary buffer.  (The other, irrelevant diary entries are really absent from the temporary buffer; in the diary buffer, they are merely hidden.)  The default value of this hook does the printing with the command lpr-buffer.  If you want to use a different command to do the printing, just change the value of this hook.  Other uses might include, for example, rearranging the lines into order by day and time.

You can customize the form of dates in your diary file, if neither the standard American nor European styles suits your needs, by setting the variable diary-date-forms.  This variable is a list of forms of dates recognized in the diary file.  Each form is a list of regular expressions (see Regexps) and the variables month, day, year, monthname, and dayname.  The variable monthname matches the name of the month, capitalized or not, or its three-letter abbreviation, followed by a period or not; it matches *.  Similarly, dayname matches the name of the day, capitalized or not, or its three-letter abbreviation, followed by a period or not.  The variables month, day, and year match those numerical values, preceded by arbitrarily many zeros; they also match *.  The default value of diary-date-forms in the American style is

     ((month "/" day "[^/0-9]")
      (month "/" day "/" year "[^0-9]")
      (monthname " *" day "[^,0-9]")
      (monthname " *" day ", *" year "[^0-9]")
      (dayname "\\W"))

Emacs matches of the diary entries with the date forms is done with the standard syntax table from Fundamental mode (see Syntax Tables (XEmacs Lisp Reference Manual)), but with the * changed so that it is a word constituent.

The forms on the list must be mutually exclusive and must not match any portion of the diary entry itself, just the date.  If, to be mutually exclusive, the pattern must match a portion of the diary entry itself, the first element of the form must be backup. This causes the date recognizer to back up to the beginning of the current word of the diary entry.  Even if you use backup, the form must absolutely not match more than a portion of the first word of the diary entry.  The default value of diary-date-forms in the European style is this list:

     ((day "/" month "[^/0-9]")
      (day "/" month "/" year "[^0-9]")
      (backup day " *" monthname "\\W+\\<[^*0-9]")
      (day " *" monthname " *" year "[^0-9]")
      (dayname "\\W"))

Notice the use of backup in the middle form because part of the diary entry must be matched to distinguish this form from the following one.

Hebrew- and Islamic-Date Diary Entries
......................................

Your diary file can have entries based on Hebrew or Islamic dates, as well as entries based on our usual Gregorian calendar.  However, because the processing of such entries is time-consuming and most people don't need them, you must customize the processing of your diary file to specify that you want such entries recognized.  If you want Hebrew-date diary entries, for example, you must include these lines in your .emacs file:

     (setq nongregorian-diary-listing-hook 'list-hebrew-diary-entries)
     (setq nongregorian-diary-marking-hook 'mark-hebrew-diary-entries)

If you want Islamic-date entries, include these lines in your .emacs file:

     (setq nongregorian-diary-listing-hook 'list-islamic-diary-entries)
     (setq nongregorian-diary-marking-hook 'mark-islamic-diary-entries)

If you want both Hebrew- and Islamic-date entries, include these lines:

     (setq nongregorian-diary-listing-hook
           '(list-hebrew-diary-entries list-islamic-diary-entries))
     (setq nongregorian-diary-marking-hook
           '(mark-hebrew-diary-entries mark-islamic-diary-entries))

Hebrew- and Islamic-date diary entries have the same formats as Gregorian-date diary entries, except that the date must be preceded with an H for Hebrew dates and an I for Islamic dates. Moreover, because the Hebrew and Islamic month names are not uniquely specified by the first three letters, you may not abbreviate them.  For example, a diary entry for the Hebrew date Heshvan 25 could look like

     HHeshvan 25 Happy Hebrew birthday!

and would appear in the diary for any date that corresponds to Heshvan 25 on the Hebrew calendar.  Similarly, an Islamic-date diary entry might be

     IDhu al-Qada 25 Happy Islamic birthday!

and would appear in the diary for any date that corresponds to Dhu al-Qada 25 on the Islamic calendar.

As with Gregorian-date diary entries, Hebrew- and Islamic-date entries are nonmarking if they are preceded with an ampersand (&).

There are commands to help you in making Hebrew- and Islamic-date entries to your diary:

i h d
     Add a diary entry for the Hebrew date corresponding to the selected date (insert-hebrew-diary-entry).

i h m
     Add a diary entry for the day of the Hebrew month corresponding to the selected date (insert-monthly-hebrew-diary-entry).

i h y
     Add a diary entry for the day of the Hebrew year corresponding to the selected date (insert-yearly-hebrew-diary-entry).

i i d
     Add a diary entry for the Islamic date corresponding to the selected date (insert-islamic-diary-entry).

i i m
     Add a diary entry for the day of the Islamic month corresponding to the selected date (insert-monthly-islamic-diary-entry).

i i y
     Add a diary entry for the day of the Islamic year corresponding to the selected date (insert-yearly-islamic-diary-entry).

These commands work exactly like the corresponding commands for ordinary diary entries: Move point to a date in the calendar window and the above commands insert the Hebrew or Islamic date (corresponding to the date indicated by point) at the end of your diary file and you can then type the diary entry.  If you want the diary entry to be nonmarking, give a numeric argument to the command.

Fancy Diary Display
...................

Diary display works by preparing the diary buffer and then running the hook diary-display-hook.  The default value of this hook hides the irrelevant diary entries and then displays the buffer (simple-diary-display).  However, if you specify the hook as follows,

     (add-hook 'diary-display-hook 'fancy-diary-display)

then fancy mode displays diary entries and holidays by copying them into a special buffer that exists only for display.  Copying provides an opportunity to change the displayed text to make it prettier---for example, to sort the entries by the dates they apply to.

As with simple diary display, you can print a hard copy of the buffer with print-diary-entries.  To print a hard copy of a day-by-day diary for a week by positioning point on Sunday of that week, type 7 d and then do M-x print-diary-entries.  As usual, the inclusion of the holidays slows down the display slightly; you can speed things up by setting the variable holidays-in-diary-buffer to nil.

Ordinarily, the fancy diary buffer does not show days for which there are no diary entries, even if that day is a holiday.  If you want such days to be shown in the fancy diary buffer, set the variable diary-list-include-blanks to t.

If you use the fancy diary display, you can use the normal hook list-diary-entries-hook to sort each day's diary entries by their time of day.  Add this line to your .emacs file:

     (add-hook 'list-diary-entries-hook 'sort-diary-entries)

For each day, this sorts diary entries that begin with a recognizable time of day according to their times.  Diary entries without times come first within each day.

Included Diary Files
....................

If you use the fancy diary display, you can have diary entries from other files included with your own by an ``include'' mechanism.  This facility makes possible the sharing of common diary files among groups of users.  Lines in the diary file of this form:

     #include "FILENAME"

includes the diary entries from the file FILENAME in the fancy diary buffer (because the ordinary diary buffer is just the buffer associated with your diary file, you cannot use the include mechanism unless you use the fancy diary buffer).  The include mechanism is recursive, by the way, so that included files can include other files, and so on; you must be careful not to have a cycle of inclusions, of course.  To enable the include facility, add lines as follows to your .emacs file:

     (add-hook 'list-diary-entries-hook 'include-other-diary-files)
     (add-hook 'mark-diary-entries-hook 'mark-included-diary-files)

Sexp Entries and the Fancy Diary Display
........................................

Sexp diary entries allow you to do more than just have complicated conditions under which a diary entry applies.  If you use the fancy diary display, sexp entries can generate the text of the entry depending on the date itself.  For example, an anniversary diary entry can insert the number of years since the anniversary date into the text of the diary entry.  Thus the %d in this dairy entry:

     %%(diary-anniversary 10 31 1948) Arthur's birthday (%d years old)

gets replaced by the age, so on October 31, 1990 the entry appears in the fancy diary buffer like this:

     Arthur's birthday (42 years old)

If the diary file instead contains this entry:

     %%(diary-anniversary 10 31 1948) Arthur's %d%s birthday

the entry in the fancy diary buffer for October 31, 1990 appears like this:

     Arthur's 42nd birthday

Similarly, cyclic diary entries can interpolate the number of repetitions that have occurred:

     %%(diary-cyclic 50 1 1 1990) Renew medication (%d%s time)

looks like this:

     Renew medication (5th time)

in the fancy diary display on September 8, 1990.

The generality of sexp diary entries lets you specify any diary entry that you can describe algorithmically.  Suppose you get paid on the 21st of the month if it is a weekday, and to the Friday before if the 21st is on a weekend.  The diary entry

     &%%(let ((dayname (calendar-day-of-week date))
              (day (car (cdr date))))
           (or (and (= day 21) (memq dayname '(1 2 3 4 5)))
               (and (memq day '(19 20)) (= dayname 5)))
              ) Pay check deposited

applies to just those dates.  This example illustrates how the sexp can depend on the variable date; this variable is a list (MONTH DAY YEAR) that gives the Gregorian date for which the diary entries are being found.  If the value of the expression is t, the entry applies to that date.  If the expression evaluates to nil, the entry does not apply to that date.

The following sexp diary entries take advantage of the ability (in the fancy diary display) to concoct diary entries based on the date:

%%(diary-sunrise-sunset)
     Make a diary entry for the local times of today's sunrise and sunset.

%%(diary-phases-of-moon)
     Make a diary entry for the phases (quarters) of the moon.

%%(diary-day-of-year)
     Make a diary entry with today's day number in the current year and the number of days remaining in the current year.

%%(diary-iso-date)
     Make a diary entry with today's equivalent ISO commercial date.

%%(diary-julian-date)
     Make a diary entry with today's equivalent date on the Julian calendar.

%%(diary-astro-day-number)
     Make a diary entry with today's equivalent astronomical (Julian) day number.

%%(diary-hebrew-date)
     Make a diary entry with today's equivalent date on the Hebrew calendar.

%%(diary-islamic-date)
     Make a diary entry with today's equivalent date on the Islamic calendar.

%%(diary-french-date)
     Make a diary entry with today's equivalent date on the French Revolutionary calendar.

%%(diary-mayan-date)
     Make a diary entry with today's equivalent date on the Mayan calendar.

Thus including the diary entry

     &%%(diary-hebrew-date)

causes every day's diary display to contain the equivalent date on the Hebrew calendar, if you are using the fancy diary display.  (With simple diary display, the line &%%(diary-hebrew-date) appears in the diary for any date, but does nothing particularly useful.)

There are a number of other available sexp diary entries that are important to those who follow the Hebrew calendar:

%%(diary-rosh-hodesh)
     Make a diary entry that tells the occurrence and ritual announcement of each new Hebrew month.

%%(diary-parasha)
     Make a Saturday diary entry that tells the weekly synagogue scripture reading.

%%(diary-sabbath-candles)
     Make a Friday diary entry that tells the local time of Sabbath candle lighting.

%%(diary-omer)
     Make a diary entry that gives the omer count, when appropriate.

%%(diary-yahrzeit MONTH DAY YEAR) NAME
     Make a diary entry marking the anniversary of a date of death.  The date is the Gregorian (civil) date of death.  The diary entry appears on the proper Hebrew calendar anniversary and on the day before.  (In the European style, the order of the parameters is changed to DAY, MONTH, YEAR.)

Customizing Appointment Reminders
.................................

You can specify exactly how Emacs reminds you of an appointment and how far in advance it begins doing so.  Here are the variables that you can set:

appt-message-warning-time
     The time in minutes before an appointment that the reminder begins.  The default is 10 minutes.

appt-audible
     If this is t (the default), Emacs rings the terminal bell for appointment reminders.

appt-visible
     If this is t (the default), Emacs displays the appointment message in echo area.

appt-display-mode-line
     If this is t (the default), Emacs displays the number of minutes to the appointment on the mode line.

appt-msg-window
     If this is t (the default), Emacs displays the appointment message in another window.

appt-display-duration
     The number of seconds an appointment message is displayed.  The default is 5 seconds.