Protesilaos Stavrou

Institution Calendar (institution-calendar.el)

Show term and week numbers in the M-x calendar for a given institution

This manual, written by Protesilaos Stavrou, describes the customization options for the Emacs package called institution-calendar (or institution-calendar.el), and provides every other piece of information pertinent to it.

The documentation furnished herein corresponds to stable version N/A, released on N/A. Any reference to a newer feature which does not yet form part of the latest tagged commit, is explicitly marked as such.

Current development target is 0.1.0-dev.

1. COPYING

Copyright (C) 2026 Protesilaos Stavrou

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual,” and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License.”

(a) The FSF’s Back-Cover Text is: “You have the freedom to copy and modify this GNU manual.”

2. Sample configuration

This basic setup covers only the universities of Oxford and Cambridge, that the package supports out-of-the-box. Though users can register their own institution and have the relevant command for it: 

(use-package institution-calendar
  :ensure nil ; not in a package archive
  :init
  ;; Install it from source.  Then upgrade it with the command
  ;; `package-vc-upgrade' or `package-vc-upgrade-all'.
  (unless (package-installed-p 'institution-calendar)
    (package-vc-install "https://github.com/protesilaos/institution-calendar.git"))
  :commands
  (institution-calendar
   institution-calendar-cambridge-university
   institution-calendar-oxford-university)
  :config
  (setopt institution-calendar-entity 'oxford-university)
  (setopt institution-calendar-include-extra-week-numbers t)
  (setopt institution-calendar-include-intermonth-header nil)

  ;; If you want to permanently change what M-x calendar shows, enable
  ;; this mode.  Otherwise, use the relevant command from the
  ;; :commands listed above.
  (institution-calendar-mode 1))

3. Overview

The institution-calendar package augments the M-x calendar buffer to include indicators about the applicable term (Display the calendar). Each term has week numbers, which are displayed on the side of the regular calendar data.

The user option institution-calendar-entity specifies which institution’s data to use. With the out-of-the-box settings, the value can be either oxford-university or cambridge-university. Though users can define their own institution, with all the relevant data (Register your own institution).

Each term shows the week numbers it formally defines. For example, the University of Oxford has three terms of 8 weeks each. When the user option institution-calendar-include-extra-week-numbers is set to a non-nil value, then an additional two weeks are added: week 0 for the week before the term starts and an extra number after the term ends. This is useful for scheduling purposes, such as to arrange meetings in preparation of the work ahead or to report on what happened over the course of the term.

The user option institution-calendar-include-intermonth-header writes text above the institution’s week indicators. This makes it a bit easier to tell them apart from the regular calendar data. For example, the University of Oxford uses OX above the week numbers.

4. Display the calendar

Enable the minor mode institution-calendar-mode to make all future calls to M-x calendar use the relevant institution data (Overview).

If you do not want to affect the M-x calendar output, then use the command institution-calendar: it is functionally equivalent to having the aforementioned minor mode enabled, except it has no permanent effect on M-x calendar—that will keep its original appearance.

If you need to check the calendar of a specific institution, then do M-x institution-calendar-cambridge-university for the University of Cambridge or M-x institution-calendar-oxford-university for the University of Oxford. Users who define their own institution, can easily generate such a command (Define a custom command for your institution).

5. Register your own institution

With the default settings, the institution-calendar package supports the universities of Oxford and Cambridge. Though users can define their own institutions. This section covers the technicalities, using a school in Austria as an example.

5.1. Write the calendar data

To register your own institution, you have to specify the data, which has the structure of institution-calendar-oxford-university-dates and thus passes the test of institution-calendar-valid-data-p. Look at the code for Oxford to get an idea. Here is a sample for a single year: 

(defvar my-austrian-school-dates
  '((2025 (wintersemester ( 9  8 2025) ( 2  6 2026))
          (sommersemester ( 2 16 2026) ( 7 10 2026)))))

This is an Austrian school that has two terms for the academic year starting in 2025: wintersemester and sommersemester. The symbols for those terms can be anything. Internally, the package uses the first letter to form the week indicator, followed by the number of the week within the given term.

Each term defines a start date and an end date as a list of integers of the form (MONTH DAY YEAR). I picked a form that is consistent with the way the built-in calendar.el represents the date, otherwise I would have used a different standard.

5.2. Register your institution

The variable institution-calendar-user-entities contains all user-defined institutions and their corresponding calendar data. Each entry is a cons cell of the form (ENTITY . CALENDAR-DATA), where ENTITY is an arbitrary symbol and CALENDAR-DATA is the symbol of a variable that holds the data, as shown in the previous section.

Here is how we can add to this list: 

(add-to-list 'institution-calendar-user-entities (cons 'austrian-school 'my-austrian-school-dates))

In this example, I am calling the newly registered institution austrian-school, which is how I can refer to it elsewhere. I am associating this austrian-school with the calendar data of the variable my-austrian-school-dates.

5.3. Make the institution-calendar-mode work for your institution

With the aforementioned in place, the user option institution-calendar-entity can be set to the value of austrian-school: 

(setopt institution-calendar-entity 'austrian-school)

If the institution-calendar-mode is enabled, then the regular calendar command will display week indicators for this school. This is good if you only need one calendar. But if you work with many institutions and thus have to switch between their calendars, then ignore this step and move to the next one. Or ignore it anyway if you prefer to keep the M-x calendar intact.

5.4. Define a custom command for your institution

The macro institution-calendar-define-convenience-command makes it trivial to define a command that produces a calendar buffer for the given institution. This is like M-x calendar with the minor mode institution-calendar-mode enabled, except it does not alter the output of the calendar—so you can use them both (or, anyhow, use as many as the institutions you care about). 

;; This defines the command `institution-calendar-austrian-school'.
;; Call `institution-calendar-austrian-school' with M-x or bind it to a key.
(institution-calendar-define-convenience-command austrian-school)

Once you evaluate this macro call, you will get the command institution-calendar-austrian-school. Use that to produce a calendar that works with the austrian-school in particular. If you are curious, M-x institution-calendar-oxford-university will still do the right thing for the University of Oxford. Same for the command institution-calendar-cambridge-university.

5.5. Use an intermonth header

The user option institution-calendar-include-intermonth-header adds a header above the week numbers. By default, this only works with the universities of Oxford and Cambridge. Though you can extend the package to support your institution by adding to the value of the variable institution-calendar-intermonth-headers. Thus: 

(add-to-list 'institution-calendar-intermonth-headers (cons 'austrian-school "AU"))

You can skip this step if you do not plan to display the intermonth header. Those are not shown by default.

5.6. Putting it all together

This is how your configuration of the institution-calendar may look like once you include the code that defines your own institution: 

(use-package institution-calendar
  :ensure nil ; not in a package archive
  :init
  ;; Install it from source.
  ;; Then upgrade it with the command `package-vc-upgrade' or `package-vc-upgrade-all'.
  (unless (package-installed-p 'institution-calendar)
    (package-vc-install "https://github.com/protesilaos/institution-calendar.git"))
  :config
  (defvar my-austrian-school-dates
    '((2025 (wintersemester ( 9  8 2025) ( 2  6 2026))
            (sommersemester ( 2 16 2026) ( 7 10 2026)))))

  (add-to-list 'institution-calendar-user-entities (cons 'austrian-school 'my-austrian-school-dates))

  ;; This defines the command `institution-calendar-austrian-school'.
  ;; Call `institution-calendar-austrian-school' with M-x or bind it to a key.
  (institution-calendar-define-convenience-command austrian-school)

  (setopt institution-calendar-include-extra-week-numbers t)
  (setopt institution-calendar-include-intermonth-header nil)

  ;; These are optional, if you want `M-x calendar' to work for your institution.
  (setopt institution-calendar-entity 'austrian-school)

  (institution-calendar-mode 1))

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