Update citations of Internet RFCs

For example, RFC 822 has been obsoleted by RFC 2822, which in
turn has been obsoleted by RFC 5322.
* doc/emacs/ack.texi, doc/lispref/os.texi:
* doc/misc/emacs-mime.texi, doc/misc/gnus-coding.texi:
* doc/misc/gnus.texi, doc/misc/sc.texi:
* lisp/calendar/parse-time.el, lisp/gnus/gnus-cite.el:
* lisp/gnus/gnus-util.el, lisp/gnus/message.el:
* lisp/gnus/mm-bodies.el, lisp/gnus/nnrss.el:
* lisp/mail/feedmail.el, lisp/mail/ietf-drums.el:
* lisp/mail/mail-extr.el, lisp/mail/mail-utils.el:
* lisp/mail/mailclient.el, lisp/mail/mailheader.el:
* lisp/mail/rfc2047.el, lisp/mail/rfc822.el, lisp/mail/rmail.el:
* lisp/mail/sendmail.el, lisp/mail/smtpmail.el:
* lisp/mail/supercite.el, lisp/mh-e/mh-e.el:
* lisp/mh-e/mh-utils.el, lisp/net/imap.el:
* lisp/net/newst-backend.el, lisp/org/org-id.el:
* lisp/ps-samp.el, lisp/simple.el, lisp/url/url-util.el:
Update RFC citations.

26 files changed, 101 insertions, 99 deletions

diff --git a/lisp/calendar/parse-time.el b/lisp/calendar/parse-time.el
index 9b404060614..41806cfc375 100644
--- a/lisp/calendar/parse-time.el
+++ b/lisp/calendar/parse-time.el
@@ -146,7 +146,7 @@ letters, digits, plus or minus signs or colons."
 ;;;###autoload
 (defun parse-time-string (string)
   "Parse the time-string STRING into (SEC MIN HOUR DAY MON YEAR DOW DST TZ).
-STRING should be on something resembling an RFC2822 string, a la
+STRING should be something resembling an RFC 822 (or later) date-time, e.g.,
 \"Fri, 25 Mar 2016 16:24:56 +0100\", but this function is
 somewhat liberal in what format it accepts, and will attempt to
 return a \"likely\" value even for somewhat malformed strings.
diff --git a/lisp/gnus/gnus-cite.el b/lisp/gnus/gnus-cite.el
index d887a205f95..d8b6df70bd4 100644
--- a/lisp/gnus/gnus-cite.el
+++ b/lisp/gnus/gnus-cite.el
@@ -94,7 +94,7 @@ The first regexp group should match the Supercite attribution."
 ;;     -----Original Message-----
 ;;     From: ...
 ;;     To: ...
-;;     Sent: ...   [date, in non-RFC-2822 format]
+;;     Sent: ...   [date, in non-RFC-822-or-later format]
 ;;     Subject: ...
 ;;
 ;;     Cited message, with no prefixes
diff --git a/lisp/gnus/gnus-util.el b/lisp/gnus/gnus-util.el
index f2f0ae98eaf..ae8cd45672e 100644
--- a/lisp/gnus/gnus-util.el
+++ b/lisp/gnus/gnus-util.el
@@ -140,7 +140,7 @@ This is a compatibility function for different Emacsen."
 
 (defun gnus-extract-address-components (from)
   "Extract address components from a From header.
-Given an RFC-822 address FROM, extract full name and canonical address.
+Given an RFC-822 (or later) address FROM, extract name and address.
 Returns a list of the form (FULL-NAME CANONICAL-ADDRESS).  Much more simple
 solution than `mail-extract-address-components', which works much better, but
 is slower."
diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 28f6fecc76a..0d166fb8ce0 100644
--- a/lisp/gnus/message.el
+++ b/lisp/gnus/message.el
@@ -1274,10 +1274,9 @@ called and its result is inserted."
              (goto-char (point-min))
              (let ((case-fold-search nil))
                (re-search-forward "^OR\\>" nil t))))
-      ;; According to RFC822, "The field-name must be composed of printable
-      ;; ASCII characters (i. e., characters that have decimal values between
-      ;; 33 and 126, except colon)", i. e., any chars except ctl chars,
-      ;; space, or colon.
+      ;; According to RFC 822 and its successors, the field name must
+      ;; consist of printable US-ASCII characters other than colon,
+      ;; i.e., decimal 33-56 and 59-126.
       '(looking-at "[ \t]\\|[][!\"#$%&'()*+,-./0-9;<=>?@A-Z\\\\^_`a-z{|}~]+:"))
   "Set this non-nil if the system's mailer runs the header and body together.
 \(This problem exists on Sunos 4 when sendmail is run in remote mode.)
@@ -1800,8 +1799,8 @@ You must have the \"hashcash\" binary installed, see `hashcash-path'."
     (concat
      "From "
 
-     ;; Many things can happen to an RFC 822 mailbox before it is put into
-     ;; a `From' line.  The leading phrase can be stripped, e.g.
+     ;; Many things can happen to an RFC 822 (or later) mailbox before it is
+     ;; put into a `From' line.  The leading phrase can be stripped, e.g.
      ;; `Joe <@w.x:joe@y.z>' -> `<@w.x:joe@y.z>'.  The <> can be stripped, e.g.
      ;; `<@x.y:joe@y.z>' -> `@x.y:joe@y.z'.  Everything starting with a CRLF
      ;; can be removed, e.g.
@@ -5697,7 +5696,7 @@ In posting styles use `(\"Expires\" (make-expires-date 30))'."
         (insert fullname)
         (goto-char (point-min))
         ;; Look for a character that cannot appear unquoted
-        ;; according to RFC 822.
+        ;; according to RFC 822 (or later).
         (when (re-search-forward "[^- !#-'*+/-9=?A-Z^-~]" nil 1)
           ;; Quote fullname, escaping specials.
           (goto-char (point-min))
@@ -5711,8 +5710,7 @@ In posting styles use `(\"Expires\" (make-expires-date 30))'."
         (let ((fullname-start (point)))
           (insert fullname)
           (goto-char fullname-start)
-          ;; RFC 822 says \ and nonmatching parentheses
-          ;; must be escaped in comments.
+          ;; \ and nonmatching parentheses must be escaped in comments.
           ;; Escape every instance of ()\ ...
           (while (re-search-forward "[()\\]" nil 1)
             (replace-match "\\\\\\&" t))
diff --git a/lisp/gnus/mm-bodies.el b/lisp/gnus/mm-bodies.el
index 23fd565d1af..298127a3f44 100644
--- a/lisp/gnus/mm-bodies.el
+++ b/lisp/gnus/mm-bodies.el
@@ -35,7 +35,7 @@
 ;; BS, vertical TAB, form feed, and ^_
 ;;
 ;; Note that CR is *not* included, as that would allow a non-paired CR
-;; in the body contrary to RFC 2822:
+;; in the body contrary to RFC 822 (or later):
 ;;
 ;;   - CR and LF MUST only occur together as CRLF; they MUST NOT
 ;;     appear independently in the body.
diff --git a/lisp/gnus/nnrss.el b/lisp/gnus/nnrss.el
index b03a2037dde..01cf7c08c98 100644
--- a/lisp/gnus/nnrss.el
+++ b/lisp/gnus/nnrss.el
@@ -446,16 +446,16 @@ nnrss: %s: Not valid XML %s and libxml-parse-html-region doesn't work %s"
 (autoload 'timezone-parse-date "timezone")
 
 (defun nnrss-normalize-date (date)
-  "Return a date string of DATE in the RFC822 style.
+  "Return a date string of DATE in the style of RFC 822 and its successors.
 This function handles the ISO 8601 date format described in
-URL `http://www.w3.org/TR/NOTE-datetime', and also the RFC822 style
+URL `http://www.w3.org/TR/NOTE-datetime', and also the RFC 822 style
 which RSS 2.0 allows."
   (let (case-fold-search vector year month day time zone cts given)
     (cond ((null date))                 ; do nothing for this case
           ;; if the date is just digits (unix time stamp):
           ((string-match "^[0-9]+$" date)
            (setq given (seconds-to-time (string-to-number date))))
-          ;; RFC822
+          ;; RFC 822
           ((string-match " [0-9]+ " date)
            (setq vector (timezone-parse-date date)
                  year (string-to-number (aref vector 0)))
diff --git a/lisp/mail/feedmail.el b/lisp/mail/feedmail.el
index e0bd4590b13..27ebe162491 100644
--- a/lisp/mail/feedmail.el
+++ b/lisp/mail/feedmail.el
@@ -560,7 +560,7 @@ but common in some proprietary systems."
 ;; maybe some distant mail system needs it.  Really, though, if you
 ;; want a sender line in your mail, just put one in there and don't
 ;; wait for feedmail to do it for you.  (Yes, I know all about
-;; RFC-822 and RFC-1123, but are you *really* one of those cases
+;; RFC-822-or-later and RFC-1123, but are you *really* one of those cases
 ;; they're talking about?  I doubt it.)
 (defcustom feedmail-sender-line nil
   "If non-nil and the email has no Sender: header, use this value.
@@ -786,7 +786,7 @@ cases the name element of the fiddle-plex is ignored and is hardwired
 by feedmail to either \"Date\" or \"Resent-Date\".
 
 If you decide to format your own date field, do us all a favor and know
-what you're doing.  Study the relevant parts of RFC-822 and RFC-1123.
+what you're doing.  Study the relevant parts of RFC-822-or-later and RFC-1123.
 Don't make me come up there!
 
 You should let feedmail generate a Date: for you unless you are sure
@@ -1514,7 +1514,7 @@ function, for example, to archive all of your sent messages someplace
 
 
 (defvar feedmail-is-a-resend nil
-  "Non-nil means the message is a Resend (in the RFC-822 sense).
+  "Non-nil means the message is a Resend (in the RFC-822-or-later sense).
 This affects the composition of certain headers.  feedmail sets this
 variable as soon as it starts prepping the message text buffer, so any
 user-supplied functions can rely on it.  Users shouldn't set or change this
@@ -2454,7 +2454,7 @@ mapped to mostly alphanumerics for safety."
 
           (let ((case-fold-search t) (addr-regexp))
             (goto-char (point-min))
-            ;; There are some RFC-822 combinations/cases missed here,
+            ;; There are some RFC-822-or-later combinations/cases missed here,
             ;; but probably good enough and what users expect.
             ;;
             ;; Use resent-* stuff only if there is at least one non-empty one.
diff --git a/lisp/mail/ietf-drums.el b/lisp/mail/ietf-drums.el
index 6501a99f7bc..bc0fc2b74e6 100644
--- a/lisp/mail/ietf-drums.el
+++ b/lisp/mail/ietf-drums.el
@@ -1,4 +1,4 @@
-;;; ietf-drums.el --- Functions for parsing RFC822bis headers
+;;; ietf-drums.el --- Functions for parsing RFC 2822 headers
 
 ;; Copyright (C) 1998-2019 Free Software Foundation, Inc.
 
@@ -20,10 +20,10 @@
 
 ;;; Commentary:
 
-;; DRUMS is an IETF Working Group that works (or worked) on the
-;; successor to RFC822, "Standard For The Format Of Arpa Internet Text
-;; Messages".  This library is based on
-;; draft-ietf-drums-msg-fmt-05.txt, released on 1998-08-05.
+;; DRUMS is an IETF Working Group that worked on Internet RFC 2822,
+;; the successor to RFC 822 and the predecessor of RFC 5322.  This
+;; library is based on draft-ietf-drums-msg-fmt-05.txt, released on
+;; 1998-08-05.
 
 ;; Pending a real regression self test suite, Simon Josefsson added
 ;; various self test expressions snipped from bug reports, and their
diff --git a/lisp/mail/mail-extr.el b/lisp/mail/mail-extr.el
index aca6dae976f..9fcc2707d75 100644
--- a/lisp/mail/mail-extr.el
+++ b/lisp/mail/mail-extr.el
@@ -1,4 +1,4 @@
-;;; mail-extr.el --- extract full name and address from RFC 822 mail header
+;;; mail-extr.el --- extract full name and address from email header
 
 ;; Copyright (C) 1991-1994, 1997, 2001-2019 Free Software Foundation,
 ;; Inc.
@@ -29,15 +29,15 @@
 ;;
 ;;    mail-extract-address-components: (address &optional all)
 ;;
-;;    Given an RFC-822 ADDRESS, extract full name and canonical address.
+;;    Given an RFC-822-or-later ADDRESS, extract name and address.
 ;;    Returns a list of the form (FULL-NAME CANONICAL-ADDRESS).
 ;;    If no name can be extracted, FULL-NAME will be nil.
 ;;    ADDRESS may be a string or a buffer.  If it is a buffer, the visible
 ;;     (narrowed) portion of the buffer will be interpreted as the address.
 ;;     (This feature exists so that the clever caller might be able to avoid
 ;;     consing a string.)
-;;    If ADDRESS contains more than one RFC-822 address, only the first is
-;;     returned.
+;;    If ADDRESS contains more than one RFC-822-or-later address, only
+;;     the first is returned.
 ;;
 ;;    If ALL is non-nil, that means return info about all the addresses
 ;;     that are found in ADDRESS.  The value is a list of elements of
@@ -149,7 +149,7 @@
 ;;      * Handle "null" addresses.  Handle = used for spacing in mailbox
 ;;        name.  Fix bug in handling of ROUTE-ADDR-type addresses that are
 ;;        missing their brackets.  Handle uppercase "JR".  Extract full
-;;        names from X.400 addresses encoded in RFC-822.  Fix bug in
+;;        names from X.400 addresses encoded in RFC-822-or-later.  Fix bug in
 ;;        handling of multiple addresses where first has trailing comment.
 ;;        Handle more kinds of telephone extension lead-ins.
 ;;
@@ -209,7 +209,7 @@
 
 
 (defgroup mail-extr nil
-  "Extract full name and address from RFC 822 mail header."
+  "Extract full name and address from RFC 822 (or later) mail header."
   :prefix "mail-extr-"
   :group 'mail)
 
@@ -288,8 +288,9 @@ by translating things like \"foo!bar!baz@host\" into \"baz@bar.UUCP\"."
 (defconst mail-extr-all-letters-but-separators
   (purecopy "][[:alnum:]{|}'~`"))
 
-;; Any character that can occur in a name in an RFC822 address including
-;; the separator (hyphen and possibly period) for multipart names.
+;; Any character that can occur in a name in an RFC 822 (or later)
+;; address including the separator (hyphen and possibly period) for
+;; multipart names.
 ;; #### should . be in here?
 (defconst mail-extr-all-letters
   (purecopy (concat mail-extr-all-letters-but-separators "---")))
@@ -532,7 +533,8 @@ by translating things like \"foo!bar!baz@host\" into \"baz@bar.UUCP\"."
     (?.  ".")
     (?\[ ".")
     (?\] ".")
-    ;; % and ! aren't RFC822 characters, but it is convenient to pretend
+    ;; % and ! aren't RFC 822 (or later) characters,
+    ;; but it is convenient to pretend.
     (?%  ".")
     (?!  ".") ;; this needs to be word-constituent when not in .UUCP mode
     )
@@ -697,7 +699,8 @@ Unless NO-REPLACE is true, at each of the positions in LIST-SYMBOL
 
 ;;;###autoload
 (defun mail-extract-address-components (address &optional all)
-  "Given an RFC-822 address ADDRESS, extract full name and canonical address.
+  "Extract full name and canonical address from ADDRESS.
+ADDRESS should be in RFC 822 (or later) format.
 Returns a list of the form (FULL-NAME CANONICAL-ADDRESS).  If no
 name can be extracted, FULL-NAME will be nil.  Also see
 `mail-extr-ignore-single-names' and
@@ -930,10 +933,10 @@ consing a string.)"
           ;; Trim other punctuation lists of items outside < > pair to handle
           ;; stupid MTAs.
           (when <-pos                   ; don't need to check >-pos also
-            ;; handle bozo software that violates RFC 822 by sticking
-            ;; punctuation marks outside of a < > pair
+            ;; Handle bozo software that violates RFC 822 (or later)
+            ;; by sticking punctuation marks outside of a < > pair.
             (mail-extr-nuke-outside-range @-pos <-pos >-pos t)
-            ;; RFC 822 says nothing about these two outside < >, but
+            ;; RFC 822 (or later) says nothing about these two outside < >, but
             ;; remove those positions from the lists to make things
             ;; easier.
             (mail-extr-nuke-outside-range !-pos <-pos >-pos t)
@@ -1319,7 +1322,7 @@ consing a string.)"
                        (narrow-to-region atom-beg atom-end)
                        (cond
 
-                        ;; Handle X.400 addresses encoded in RFC-822.
+                        ;; Handle X.400 addresses encoded in RFC 822 or later.
                         ;; *** Shit!  This has to handle the case where it is
                         ;; *** embedded in a quote too!
                         ;; *** Shit!  The input is being broken up into atoms
diff --git a/lisp/mail/mail-utils.el b/lisp/mail/mail-utils.el
index 36928b1eb21..0d489499f59 100644
--- a/lisp/mail/mail-utils.el
+++ b/lisp/mail/mail-utils.el
@@ -29,7 +29,7 @@
 
 ;;;###autoload
 (defcustom mail-use-rfc822 nil
-  "If non-nil, use a full, hairy RFC822 parser on mail addresses.
+  "If non-nil, use a full, hairy RFC 822 (or later) parser on mail addresses.
 Otherwise, (the default) use a smaller, somewhat faster, and
 often correct parser."
   :type 'boolean
@@ -384,7 +384,7 @@ The buffer should be narrowed to just the header."
          (date (mail-fetch-field "date"))
          ;; A From: header can contain multiple addresses, a "From "
          ;; line must contain only one.  (Bug#7760)
-         ;; See eg RFC 5322, 3.6.2. Originator Fields.
+         ;; See, e.g., RFC 5322, 3.6.2. Originator Fields.
          (end (string-match "[ \t]*[,\n]" from)))
     (format "From %s %s\n" (if end
                                (substring from 0 end)
diff --git a/lisp/mail/mailclient.el b/lisp/mail/mailclient.el
index 5dd66ff8452..4d8cda10fff 100644
--- a/lisp/mail/mailclient.el
+++ b/lisp/mail/mailclient.el
@@ -152,7 +152,7 @@ The mail client is taken to be the handler of mailto URLs."
                   (setq character-coding (downcase character-coding)))
                 (concat
                  "mailto:"
-                 ;; some of the headers according to RFC822
+                 ;; Some of the headers according to RFC 822 (or later).
                  (mailclient-gather-addresses "To"
                                               'drop-first-name)
                  (mailclient-gather-addresses "cc"  )
diff --git a/lisp/mail/mailheader.el b/lisp/mail/mailheader.el
index 0db4df063e3..936f53e96a5 100644
--- a/lisp/mail/mailheader.el
+++ b/lisp/mail/mailheader.el
@@ -23,7 +23,7 @@
 
 ;;; Commentary:
 
-;; This package provides an abstraction to RFC822-style messages, used in
+;; This package provides an abstraction of RFC 822 (or later) format, used in
 ;; mail, news, and some other systems.  The simple syntactic rules for such
 ;; headers, such as quoting and line folding, are routinely reimplemented
 ;; in many individual packages.  This package removes the need for this
diff --git a/lisp/mail/rfc2047.el b/lisp/mail/rfc2047.el
index 87c4cfb7a1a..a1c65cbe930 100644
--- a/lisp/mail/rfc2047.el
+++ b/lisp/mail/rfc2047.el
@@ -340,7 +340,7 @@ The buffer may be narrowed."
 
 ;; Use this syntax table when parsing into regions that may need
 ;; encoding.  Double quotes are string delimiters, backslash is
-;; character quoting, and all other RFC 2822 special characters are
+;; character quoting, and all other RFC 822 (or later) special characters are
 ;; treated as punctuation so we can use forward-sexp/forward-word to
 ;; skip to the end of regions appropriately.  Nb. ietf-drums does
 ;; things differently.
@@ -368,7 +368,7 @@ The buffer may be narrowed."
 
 (defun rfc2047-encode-region (b e &optional dont-fold)
   "Encode words in region B to E that need encoding.
-By default, the region is treated as containing RFC2822 addresses.
+By default, the region is treated as containing RFC 822 (or later) addresses.
 Dynamically bind `rfc2047-encoding-type' to change that."
   (save-restriction
     (narrow-to-region b e)
@@ -405,7 +405,7 @@ Dynamically bind `rfc2047-encoding-type' to change that."
         (with-syntax-table rfc2047-syntax-table
           (goto-char (point-min))
           (condition-case err           ; in case of unbalanced quotes
-              ;; Look for rfc2822-style: sequences of atoms, quoted
+              ;; Look for RFC 822 (or later) style: sequences of atoms, quoted
               ;; strings, specials, whitespace.  (Specials mustn't be
               ;; encoded.)
               (while (not (eobp))
@@ -1027,7 +1027,7 @@ other than `\"' and `\\' in quoted strings."
               (replace-match " "))
             (setq end (point-max))
             ;; Quote decoded words if there are special characters
-            ;; which might violate RFC2822.
+            ;; which might violate RFC 822 (or later).
             (when (and rfc2047-quote-decoded-words-containing-tspecials
                        (let ((regexp (car (rassq
                                            'address-mime
diff --git a/lisp/mail/rfc822.el b/lisp/mail/rfc822.el
index 594416f12d7..a53a77e47ee 100644
--- a/lisp/mail/rfc822.el
+++ b/lisp/mail/rfc822.el
@@ -1,4 +1,4 @@
-;;; rfc822.el --- hairy rfc822 parser for mail and news and suchlike
+;;; rfc822.el --- hairy RFC 822 (or later) parser for mail, news, etc.
 
 ;; Copyright (C) 1986-1987, 1990, 2001-2019 Free Software Foundation,
 ;; Inc.
@@ -24,8 +24,8 @@
 
 ;;; Commentary:
 
-;; Support functions for parsing RFC-822 headers, used by mail and news
-;; modes.
+;; Support functions for parsing headers used by mail and news modes.
+;; The header format is specified by Internet RFC 822 and its successors.
 
 ;;; Code:
 
diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index 8a75f1fba91..a740c4bfa23 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -785,8 +785,8 @@ The first parenthesized expression should match the MIME-charset name.")
     (concat
      "From "
 
-     ;; Many things can happen to an RFC 822 mailbox before it is put into
-     ;; a `From' line.  The leading phrase can be stripped, e.g.
+     ;; Many things can happen to an RFC 822 (or later) mailbox before it is
+     ;; put into a `From' line.  The leading phrase can be stripped, e.g.
      ;; `Joe <@w.x:joe@y.z>' -> `<@w.x:joe@y.z>'.  The <> can be stripped, e.g.
      ;; `<@x.y:joe@y.z>' -> `@x.y:joe@y.z'.  Everything starting with a CRLF
      ;; can be removed, e.g.
@@ -1009,8 +1009,8 @@ If `rmail-display-summary' is non-nil, make a summary for this RMAIL file."
   "Report that the buffer is not in the mbox file format.
 MSGNUM, if present, indicates the malformed message."
   (if msgnum
-      (error "Message %d is not a valid RFC2822 message" msgnum)
-    (error "Message is not a valid RFC2822 message")))
+      (error "Message %d is not a valid RFC 822 (or later) message" msgnum)
+    (error "Message is not a valid RFC 822 (or later) message")))
 
 (defun rmail-convert-babyl-to-mbox ()
   "Convert the mail file from Babyl version 5 to mbox.
@@ -2155,9 +2155,9 @@ Call with point at the end of the message."
     (insert "\n")))
 
 (defun rmail-add-mbox-headers ()
-  "Validate the RFC2822 format for the new messages.
+  "Validate the RFC 822 (or later) format for the new messages.
 Point should be at the first new message.
-An error is signaled if the new messages are not RFC2822
+An error is signaled if the new messages are not RFC 822 (or later)
 compliant.
 Unless an Rmail attribute header already exists, add it to the
 new messages.  Return the number of new messages."
@@ -3928,9 +3928,9 @@ which is an element of rmail-msgref-vector."
              (setq tem (copy-sequence tem))
              (set-text-properties 0 (length tem) nil tem)
              (setq tem (copy-sequence tem))
-             ;; Use prin1 to fake RFC822 quoting
+             ;; Use prin1 to fake RFC 822 (or later) quoting
              (let ((field (prin1-to-string tem)))
-               ;; Wrap it in parens to make it a comment according to RFC822
+               ;; Wrap it in parens to make it a comment.
                (if date
                    (concat "(" field "'s message of " date ")")
                  (concat "(" field ")"))))))
@@ -3959,7 +3959,7 @@ which is an element of rmail-msgref-vector."
              (if message-id
                  ;; "<AA259@bar.edu> (message from Unix Loser on 1-Apr-89)"
                  (concat message-id " (" field ")")
-               ;; Wrap in parens to make it a comment, for RFC822.
+               ;; Wrap in parens to make it a comment.
                (concat "(" field ")")))))
         (t
          ;; If we can't kludge it simply, do it correctly
diff --git a/lisp/mail/sendmail.el b/lisp/mail/sendmail.el
index 58a2cd16011..21c85dae2cf 100644
--- a/lisp/mail/sendmail.el
+++ b/lisp/mail/sendmail.el
@@ -147,7 +147,7 @@ Otherwise, let mailer send back a message to report errors."
       'smtpmail-send-it 'sendmail-query-once)
   "Function to call to send the current buffer as mail.
 The headers should be delimited by a line which is
-not a valid RFC822 header or continuation line,
+not a valid RFC 822 (or later) header or continuation line,
 that matches the variable `mail-header-separator'.
 This is used by the default mail-sending commands.  See also
 `message-send-mail-function' for use with the Message package."
@@ -905,7 +905,7 @@ the user from the mailer."
             (ml (when mail-mailing-lists
                 ;; The surrounding regexp assumes the use of
                 ;; `mail-strip-quoted-names' on addresses before matching
-                ;; Cannot deal with full RFC 822 freedom, but that is
+                ;; Cannot deal with full RFC 822 (or later), but that is
                 ;; unlikely to be problematic.
                 (concat "\\(?:[[:space:];,]\\|\\`\\)"
                         (regexp-opt mail-mailing-lists t)
@@ -1041,7 +1041,7 @@ This function does not perform RFC2047 encoding."
                  (fullname-end (point-marker)))
              (goto-char fullname-start)
              ;; Look for a character that cannot appear unquoted
-             ;; according to RFC 822.
+             ;; according to RFC 822 (or later).
              (if (or (re-search-forward "[^- !#-'*+/-9=?A-Z^-~]"
                                         fullname-end 1)
                      quote-fullname)
@@ -1065,8 +1065,7 @@ This function does not perform RFC2047 encoding."
                  (insert "\""))
              (let ((fullname-end (point-marker)))
                (goto-char fullname-start)
-               ;; RFC 822 says \ and nonmatching parentheses
-               ;; must be escaped in comments.
+               ;; \ and nonmatching parentheses must be escaped in comments.
                ;; Escape every instance of ()\ ...
                (while (re-search-forward "[()\\]" fullname-end 1)
                  (replace-match "\\\\\\&" t))
diff --git a/lisp/mail/smtpmail.el b/lisp/mail/smtpmail.el
index 5b28c271038..0043fafb4a0 100644
--- a/lisp/mail/smtpmail.el
+++ b/lisp/mail/smtpmail.el
@@ -256,7 +256,7 @@ The list is in preference order.")
                                (fullname-end (point-marker)))
                            (goto-char fullname-start)
                            ;; Look for a character that cannot appear unquoted
-                           ;; according to RFC 822.
+                           ;; according to RFC 822 or its successors.
                            (if (re-search-forward "[^- !#-'*+/-9=?A-Z^-~]"
                                                   fullname-end 1)
                                (progn
@@ -274,8 +274,9 @@ The list is in preference order.")
                            (insert fullname)
                            (let ((fullname-end (point-marker)))
                              (goto-char fullname-start)
-                             ;; RFC 822 says \ and nonmatching parentheses
-                             ;; must be escaped in comments.
+                             ;; RFC 822 and its successors say \ and
+                             ;; nonmatching parentheses must be
+                             ;; escaped in comments.
                              ;; Escape every instance of ()\ ...
                              (while (re-search-forward "[()\\]" fullname-end 1)
                                (replace-match "\\\\\\&" t))
diff --git a/lisp/mail/supercite.el b/lisp/mail/supercite.el
index 9570f533134..4809c33abc4 100644
--- a/lisp/mail/supercite.el
+++ b/lisp/mail/supercite.el
@@ -315,7 +315,7 @@ during the initial citing via `sc-cite-original'."
   :group 'supercite-hooks)
 
 (defcustom sc-mail-warn-if-non-rfc822-p t
-  "Warn if mail headers don't conform to RFC822."
+  "Warn if mail headers don't conform to RFC 822 (or later)."
   :type 'boolean
   :group 'supercite-attr)
 (defcustom sc-mumble ""
@@ -745,10 +745,10 @@ If optional ATTRIBS-P is non-nil, the key/value pair is placed in
   nil)
 
 (defun sc-mail-error-in-mail-field ()
-  "Issue warning that mail headers don't conform to RFC 822."
+  "Issue warning that mail headers don't conform to email RFCs."
   (let* ((len (min (length curline) 10))
          (ellipsis (if (< len (length curline)) "..." ""))
-         (msg "Mail header \"%s%s\" doesn't conform to RFC 822. skipping..."))
+         (msg "Mail header \"%s%s\" doesn't conform to RFC 822 (or later). skipping..."))
     (message msg (substring curline 0 len) ellipsis))
   (beep)
   (sit-for 2)
diff --git a/lisp/mh-e/mh-e.el b/lisp/mh-e/mh-e.el
index 571c0b5c4d3..ee938166931 100644
--- a/lisp/mh-e/mh-e.el
+++ b/lisp/mh-e/mh-e.el
@@ -2413,14 +2413,14 @@ of citations entirely, choose \"None\"."
   :package-version '(MH-E . "8.0"))
 
 ;; These entries have been intentionally excluded by the developers.
-;;  "Comments:"                         ; RFC 2822 - show this one
+;;  "Comments:"                         ; RFC 822 (or later) - show this one
 ;;  "Fax:"                              ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
 ;;  "Mail-System-Version:"              ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
 ;;  "Mailer:"                           ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
 ;;  "Organization:"                     ;
 ;;  "Phone:"                            ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
 ;;  "Reply-By:"                         ; RFC 2156
-;;  "Reply-To:"                         ; RFC 2822
+;;  "Reply-To:"                         ; RFC 822 (or later)
 ;;  "Sender:"                           ;
 ;;  "User-Agent:"                       ; Similar to X-Mailer, so display it.
 ;;  "X-Mailer:"                         ;
@@ -2481,9 +2481,9 @@ of citations entirely, choose \"None\"."
     "From "                             ; sendmail
     "Generate-Delivery-Report:"         ; RFC 2156
     "Importance:"                       ; RFC 2156, 2421
-    "In-Reply-To:"                      ; RFC 2822
+    "In-Reply-To:"                      ; RFC 822 (or later)
     "Incomplete-Copy:"                  ; RFC 2156
-    "Keywords:"                         ; RFC 2822
+    "Keywords:"                         ; RFC 822 (or later)
     "Language:"                         ; RFC 2156
     "Lines:"                            ; RFC 1036
     "List-"                             ; RFC 2369, 2919
@@ -2493,7 +2493,7 @@ of citations entirely, choose \"None\"."
     "Mail-Reply-To:"                    ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
     "Mailing-List:"                     ; Egroups/yahoogroups mailing list manager
     "Message-Content:"                  ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
-    "Message-Id:"                       ; RFC 822
+    "Message-ID:"                       ; RFC 822 (or later)
     "Message-Type:"                     ; RFC 2156
     "Mime-Version"                      ; RFC 2045
     "Msgid:"
@@ -2524,14 +2524,14 @@ of citations entirely, choose \"None\"."
     "Priority:"                         ; RFC 2156
     "Read-Receipt-To:"                  ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
     "Received-SPF:"                     ; Gmail
-    "Received:"                         ; RFC 822
-    "References:"                       ; RFC 2822
+    "Received:"                         ; RFC 822 (or later)
+    "References:"                       ; RFC 822 (or later)
     "Registered-Mail-Reply-Requested-By:"       ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
     "Remailed-"                         ; MH
     "Replaces:"                         ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
     "Replied:"                          ; MH
-    "Resent-"                           ; RFC 2822
-    "Return-Path:"                      ; RFC 822
+    "Resent-"                           ; RFC 822 (or later)
+    "Return-Path:"                      ; RFC 822 (or later)
     "Return-Receipt-Requested:"         ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
     "Return-Receipt-To:"                ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
     "Seal-Send-Time:"
diff --git a/lisp/mh-e/mh-utils.el b/lisp/mh-e/mh-utils.el
index 34f902a65e6..7cba9a5f417 100644
--- a/lisp/mh-e/mh-utils.el
+++ b/lisp/mh-e/mh-utils.el
@@ -887,7 +887,7 @@ in this situation."
 ;;;###mh-autoload
 (defun mh-header-field-beginning ()
   "Move to the beginning of the current header field.
-Handles RFC 822 continuation lines."
+Handle RFC 822 (or later) continuation lines."
   (beginning-of-line)
   (while (looking-at "^[ \t]")
     (forward-line -1)))
@@ -895,7 +895,7 @@ Handles RFC 822 continuation lines."
 ;;;###mh-autoload
 (defun mh-header-field-end ()
   "Move to the end of the current header field.
-Handles RFC 822 continuation lines."
+Handle RFC 822 (or later) continuation lines."
   (forward-line 1)
   (while (looking-at "^[ \t]")
     (forward-line 1))
diff --git a/lisp/net/imap.el b/lisp/net/imap.el
index f4ae7b94495..dedf5f794a4 100644
--- a/lisp/net/imap.el
+++ b/lisp/net/imap.el
@@ -2094,23 +2094,23 @@ Return nil if no complete line has arrived."
 ;;                      addr-host ")"
 ;;
 ;;   addr-adl        = nstring
-;;                       ; Holds route from [RFC-822] route-addr if
+;;                       ; Holds route from [RFC-822 (or later)] route-addr if
 ;;                       ; non-nil
 ;;
 ;;   addr-host       = nstring
-;;                       ; nil indicates [RFC-822] group syntax.
-;;                       ; Otherwise, holds [RFC-822] domain name
+;;                       ; nil indicates [RFC-822 (or later)] group syntax.
+;;                       ; Otherwise, holds [RFC-822 (or later)] domain name
 ;;
 ;;   addr-mailbox    = nstring
-;;                       ; nil indicates end of [RFC-822] group; if
+;;                       ; nil indicates end of [RFC-822 (or later)] group; if
 ;;                       ; non-nil and addr-host is nil, holds
-;;                       ; [RFC-822] group name.
-;;                       ; Otherwise, holds [RFC-822] local-part
-;;                       ; after removing [RFC-822] quoting
+;;                       ; [RFC-822 (or later)] group name.
+;;                       ; Otherwise, holds [RFC-822 (or later)] local-part
+;;                       ; after removing [RFC-822 (or later)] quoting
 ;;
 ;;   addr-name       = nstring
-;;                       ; If non-nil, holds phrase from [RFC-822]
-;;                       ; mailbox after removing [RFC-822] quoting
+;;                       ; If non-nil, holds phrase from [RFC-822 (or later)]
+;;                       ; mailbox after removing [RFC-822 (or later)] quoting
 ;;
 
 (defsubst imap-parse-address ()
diff --git a/lisp/net/newst-backend.el b/lisp/net/newst-backend.el
index 94101fb0b25..96503bae18b 100644
--- a/lisp/net/newst-backend.el
+++ b/lisp/net/newst-backend.el
@@ -1699,8 +1699,8 @@ Examples:
     nil))
 
 (defun newsticker--decode-rfc822-date (rfc822-string)
-  "Return RFC822-STRING in format like `decode-time'.
-Converts from RFC822 to Emacs representation.
+  "Convert RFC822-STRING to a Lisp timestamp.
+RFC822-STRING should use RFC 822 (or later) format.
 Examples:
 Sat, 07 September 2002 00:00:01 +0100
 Sat, 07 September 2002 00:00:01 MET
diff --git a/lisp/org/org-id.el b/lisp/org/org-id.el
index 4de99f363a6..994aa7e3e83 100644
--- a/lisp/org/org-id.el
+++ b/lisp/org/org-id.el
@@ -160,9 +160,9 @@ to have no space characters in them."
 (defcustom org-id-include-domain nil
   "Non-nil means add the domain name to new IDs.
 This ensures global uniqueness of IDs, and is also suggested by
-RFC 2445 in combination with RFC 822.  This is only relevant if
-`org-id-method' is `org'.  When uuidgen is used, the domain will never
-be added.
+the relevant RFCs.  This is relevant only if `org-id-method' is
+`org'.  When uuidgen is used, the domain will never be added.
+
 The default is to not use this because we have no really good way to get
 the true domain, and Org entries will normally not be shared with enough
 people to make this necessary."
diff --git a/lisp/ps-samp.el b/lisp/ps-samp.el
index 1888f1a8192..cccf035834f 100644
--- a/lisp/ps-samp.el
+++ b/lisp/ps-samp.el
@@ -76,8 +76,8 @@
       (concat "Subject: " (or (mail-fetch-field "Subject") "???")))))
 
 ;; Look in an article or mail message for the From: line.  Sorta-kinda
-;; understands RFC-822 addresses and can pull the real name out where
-;; it's provided.
+;; understands RFC 822 (or later) addresses and can pull the real name
+;; out where it's provided.
 (defun ps-article-author ()
   (save-excursion
     (save-restriction
diff --git a/lisp/simple.el b/lisp/simple.el
index 4c55278b1f1..2646d7b0259 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -7829,7 +7829,7 @@ appears to have customizations applying to the old default,
   "If the buffer starts with a mail header, move point to the header's end.
 Otherwise, moves to `point-min'.
 The end of the header is the start of the next line, if there is one,
-else the end of the last line.  This function obeys RFC822."
+else the end of the last line.  This function obeys RFC 822 (or later)."
   (goto-char (point-min))
   (when (re-search-forward
          "^\\([:\n]\\|[^: \t\n]+[ \t\n]\\)" nil 'move)
diff --git a/lisp/url/url-util.el b/lisp/url/url-util.el
index 11ee15fdd4e..95e808f764d 100644
--- a/lisp/url/url-util.el
+++ b/lisp/url/url-util.el
@@ -74,7 +74,8 @@ If a list, it is a list of the types of messages to be logged."
 
 ;;;###autoload
 (defun url-parse-args (str &optional nodowncase)
-  ;; Return an assoc list of attribute/value pairs from an RFC822-type string
+  ;; Return an assoc list of attribute/value pairs from a string
+  ;; that uses RFC 822 (or later) format.
   (let (
         name                            ; From name=
         value                           ; its value