; Improve commentary in calendar.el

* lisp/calendar/calendar.el: Expand the commentary.  Suggested by
Richard Lawrence <rwl@recursewithless.net>.  (Bug#74965)

(cherry picked from commit 6902673b5b9c641fd2df3881533d6fc343124371)

diff --git a/lisp/calendar/calendar.el b/lisp/calendar/calendar.el
index 63a8504a8554c6bbbcaa4811c606ca250c2337ac..e1e87726e7777d3e0adefaa7c8a7ee3b14107202 100644 (file)
--- a/lisp/calendar/calendar.el
+++ b/lisp/calendar/calendar.el
@@ -96,10 +96,13 @@
 ;; list of integers (MONTH DAY YEAR) -- see the functions
 ;; `calendar-extract-year', `calendar-extract-month', and
 ;; `calendar-extract-day'.  Internally it also uses an "absolute" format
-;; which is an integer number of days since December 31, 1BC (see
-;; e.g. `calendar-absolute-from-gregorian'), and converts between
-;; different calendar scales by converting to and from the absolute
-;; format (see e.g. `calendar-iso-from-absolute' in cal-iso.el).
+;; which is an integer number of days since December 31, 1BC on the
+;; Gregorian calendar (see e.g. `calendar-absolute-from-gregorian'), and
+;; converts between different calendar scales by converting to and from
+;; the absolute format (see e.g. `calendar-iso-from-absolute' in
+;; cal-iso.el).  This representation is also useful for certain
+;; calculations; e.g. `calendar-day-of-week' is simply the absolute
+;; represention modulo 7, because December 31, 1BC is a Sunday.
 
 ;; A note on free variables: