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diff --git a/lisp/obsolete/url-about.el b/lisp/obsolete/url-about.el
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+;;; url-about.el --- Show internal URLs  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2001-2022 Free Software Foundation, Inc.
+
+;; Keywords: comm, data, processes, hypermedia
+;; Obsolete-since: 29.1
+
+;; This file is part of GNU Emacs.
+;;
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'url-util)
+(require 'url-parse)
+
+(defun url-probe-protocols ()
+  "Return a list of all potential URL schemes."
+  (or (get 'url-extension-protocols 'probed)
+      (mapc (lambda (s) (url-scheme-get-property s 'name))
+	    (or (get 'url-extension-protocols 'schemes)
+		(let ((schemes '("info" "man" "rlogin" "telnet"
+				 "tn3270" "data" "snews")))
+		  (mapc (lambda (d)
+			  (mapc (lambda (f)
+				  (if (string-match "url-\\(.*\\).el$" f)
+				      (push (match-string 1 f) schemes)))
+				(directory-files d nil "\\`url-.*\\.el\\'")))
+                        (seq-filter #'file-exists-p load-path))
+		  (put 'url-extension-protocols 'schemes schemes)
+		  schemes)))))
+
+(defvar url-scheme-registry)
+
+(defun url-about-protocols (_url)
+  (url-probe-protocols)
+  (insert "<html>\n"
+	  " <head>\n"
+	  "  <title>Supported Protocols</title>\n"
+	  " </head>\n"
+	  " <body>\n"
+          "  <h1>Supported Protocols - URL package in Emacs " emacs-version "</h1>\n"
+	  "  <table width='100%' border='1'>\n"
+	  "   <tr>\n"
+	  "    <td>Protocol\n"
+	  "    <td>Properties\n"
+	  "    <td>Description\n"
+	  "   </tr>\n")
+  (mapc (lambda (k)
+	  (if (string= k "proxy")
+	      ;; Ignore the proxy setting... its magic!
+	      nil
+	    (insert "   <tr>\n")
+	    ;; The name of the protocol
+	    (insert "    <td valign=top>" (or (url-scheme-get-property k 'name) k) "\n")
+
+	    ;; Now the properties.  Currently just asynchronous
+	    ;; status, default port number, and proxy status.
+	    (insert "    <td valign=top>"
+		    (if (url-scheme-get-property k 'asynchronous-p) "As" "S")
+		    "ynchronous<br>\n"
+		    (if (url-scheme-get-property k 'default-port)
+			(format "Default Port: %d<br>\n"
+				(url-scheme-get-property k 'default-port))
+		      "")
+		    (if (assoc k url-proxy-services)
+			(format "Proxy: %s<br>\n" (assoc k url-proxy-services)) ""))
+	    ;; Now the description...
+	    (insert "    <td valign=top>"
+		    (or (url-scheme-get-property k 'description) "N/A"))))
+	(sort (let (x) (maphash (lambda (k _v) (push k x)) url-scheme-registry) x)
+	      #'string-lessp))
+  (insert "  </table>\n"
+	  " </body>\n"
+	  "</html>\n"))
+
+(defun url-about (url)
+  "Show internal URLs."
+  (let* ((item (downcase (url-filename url)))
+	 (func (intern (format "url-about-%s" item))))
+    (if (fboundp func)
+	(progn
+	  (set-buffer (generate-new-buffer " *about-data*"))
+	  (insert "Content-type: text/plain\n\n")
+	  (funcall func url)
+	  (current-buffer))
+      (error "URL does not know about `%s'" item))))
+
+(provide 'url-about)
+
+;;; url-about.el ends here