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This is Info file ../info/w3.info, produced by Makeinfo version 1.68 from the input file w3.texi. INFO-DIR-SECTION World Wide Web INFO-DIR-SECTION GNU Emacs Lisp START-INFO-DIR-ENTRY * Emacs/W3: (w3). Emacs/W3 World Wide Web browser. END-INFO-DIR-ENTRY This file documents the Emacs/W3 World Wide Web browser. Copyright (C) 1993, 1994, 1995, 1996 William M. Perry Copyright (C) 1996, 1997 Free Software Foundation Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. File: w3.info, Node: MIME Support, Next: Security, Prev: Supported URLs, Up: Top MIME Support ************ MIME is an emerging standard for multimedia mail. It offers a very flexible typing mechanism. The type of a file or message is specified in two parts, separated by a '/'. The first part is the general category of the data (text, application, image, etc.). The second part is the specific type of data (postscript, png, jpeg, etc.). So `text/html' specifies an HTML document, whereas `image/x-xwindowdump' specifies an image of an Xwindow taken with the `xwd' program. This typing allows much more flexibility in naming files. HTTP/1.0 servers can now send back content-type headers in response to a request, and not have the client second-guess it based on file extensions. HTML files can now be named `something.png' (not a great idea, but possible). * Menu: * Adding MIME types based on file extensions:: How to map file extensions onto MIME types (e.g., `.png -> image/png)'. * Specifying Viewers:: How to specify external and internal viewers for files that Emacs/W3 cannot handle natively. File: w3.info, Node: Adding MIME types based on file extensions, Next: Specifying Viewers, Prev: MIME Support, Up: MIME Support Adding MIME types based on file extensions ========================================== For some protocols however, it is still necessary to guess the content of a file based on the file extension. This type of guess-work should only be needed when accessing files via FTP, local file access, or old HTTP/0.9 servers. Instead of specifying how to view things twice, once based on content-type and once based on the file extension, it is easier to map file extensions to MIME content-types. The variable that controls this is `mm-mime-extensions'. This variable is an assoc list of file extensions and the corresponding MIME content-type. A sample entry looks like: `(".movie" . "video/x-sgi-movie")' This makes all files that end in `.movie' (`foo.movie' and `bar.movie') be interpreted as SGI animation files. If a content-type is defined for the document, then this is over-ridden. Regular expressions can NOT be used. Both Mosaic and the NCSA HTTP daemon rely on a separate file for mapping file extensions to MIME types. Instead of having the users of Emacs/W3 duplicate this in lisp, this file can be parsed using the `url-parse-mimetypes' function. This function is called each time w3 is loaded. It tries to locate mimetype files in several places. If the environment variable `MIMETYPES' is nonempty, then this is assumed to specify a UNIX-like path of mimetype files (this is a colon separated string of pathnames). If the `MIMETYPES' environment variable is empty, then Emacs/W3 looks for these files: 1. `~/.mime-types' 2. `/etc/mime-types' 3. `/usr/etc/mime-types' 4. `/usr/local/etc/mime-types' 5. `/usr/local/www/conf/mime-types' Each line contains information for one HTTP type. These types resemble MIME types. To add new ones, use subtypes beginning with x-, such as application/x-myprogram. Lines beginning with # are comment lines, and suitably ignored. Each line consists of: type/subtype ext1 ext2 ... extN type/subtype is the MIME-like type of the document. ext* is any number of space-separated filename extensions which correspond to the MIME type. File: w3.info, Node: Specifying Viewers, Prev: Adding MIME types based on file extensions, Up: MIME Support Specifying Viewers ================== Not all files look as they should when parsed as an HTML document (whitespace is stripped, paragraphs are reformatted, and lots of little changes that make the document look unrecognizable). Files may be passed to external programs or Emacs Lisp functions to be viewed. Not all files can be viewed accurately from within an Emacs session (PNG files for example, or audio files). For this reason, the user can specify file "viewers" based on MIME content-types. This is done with a standard mailcap file. *Note Mailcap Files:: As an alternative, the function `mm-add-mailcap-entry' can also be used from an appropriate hook.*Note Hooks:: This functions takes three arguments, the major type ("image"), the minor type ("png"), and an assoc list of information about the viewer. Please see the URL documentation for more specific information on what this assoc list should look like. File: w3.info, Node: Security, Next: Non-Unix Operating Systems, Prev: MIME Support, Up: Top Security ******** There are an increasing number of ways to authenticate a user to a web service. Emacs/W3 tries to support as many as possible. Emacs/W3 currently supports: Basic Authentication The weakest authentication available, not recommended if serious security is necessary. This is simply a string that looks like `user:password' that has been Base64 encoded, as defined in RFC 1421. Digest Authentication Jeffery L. Hostetler, John Franks, Philip Hallam-Baker, Ari Luotonen, Eric W. Sink, and Lawrence C. Stewart have an internet draft for a new authentication mechanism. For the complete specification, please see draft-ietf-http-digest-aa-01.txt in the nearest internet drafts archive(1). SSL Encryption SSL is the `Secure Sockets Layer' interface developed by Netscape Communications (2). Emacs/W3 supports HTTP transfers over an SSL encrypted channel, if the appropriate files have been installed.*Note Installing SSL:: ---------- Footnotes ---------- (1) One is ftp://ds.internic.net/internet-drafts (2) http://www.netscape.com/ File: w3.info, Node: Non-Unix Operating Systems, Next: Speech Integration, Prev: Security, Up: Top Non-Unix Operating Systems ************************** * Menu: * VMS:: The wonderful world of VAX|AXP-VMS! * OS/2:: The next-best thing to Unix. * MS-DOS:: The wonderful world of MS-DOG! * Windows:: Windows NT, Chicago/Windows 95. File: w3.info, Node: VMS, Next: OS/2, Prev: Non-Unix Operating Systems, Up: Non-Unix Operating Systems VMS === :: WORK :: VMS Specific instriuctions File: w3.info, Node: OS/2, Next: MS-DOS, Prev: VMS, Up: Non-Unix Operating Systems OS/2 ==== :: WORK :: OS/2 Specific instructions File: w3.info, Node: MS-DOS, Next: Windows, Prev: OS/2, Up: Non-Unix Operating Systems MS-DOS ====== :: WORK :: DOS Specific instructions File: w3.info, Node: Windows, Prev: MS-DOS, Up: Non-Unix Operating Systems Windows ======= :: WORK :: 32bit Windows Specific instructions File: w3.info, Node: Speech Integration, Next: Advanced Features, Prev: Non-Unix Operating Systems, Up: Top Speech Integration ****************** :: WORK :: Emacspeak integration File: w3.info, Node: Advanced Features, Next: More Help, Prev: Speech Integration, Up: Top Advanced Features ***************** * Menu: * Disk Caching:: Improving performance by using a local disk cache * Interfacing to Mail/News:: How to make VM understand hypertext links * Debugging HTML:: How to make Emacs/W3 display warnings about invalid HTML/HTML+ constructs. * Hooks:: Various hooks to use throughout Emacs/W3 * Other Variables:: Miscellaneous variables that control the real guts of Emacs/W3. File: w3.info, Node: Disk Caching, Next: Interfacing to Mail/News, Prev: Advanced Features, Up: Advanced Features Disk Caching ============ A cache stores the information on a page on the local machine. When requesting a page that is in the cache, Emacs/W3 can retrieve the page from the cache more quickly than retrieving the page again from its location out on the network. With a well-populated cache, browsing the web is dramatically faster. The first time a page is requested, Emacs/W3 retrieves the page from the network. When requesting a page that is in the cache, Emacs/W3 checks to see if the page has changed since it was last retrieved from the remote machine. If it has not changed, the local copy is used, saving the transmission of the file over the network. To turn on disk caching, set the variable `url-automatic-caching' to non-`nil', or choose the 'Caching' menu item (under `Options'). That is all there is to it. Running the `clean-cache' shell script fist is recommended, to allow for future cleaning of the cache. This shell script will remove all files that have not been accessed since it was last run. To keep the cache pared down, it is recommended that this script be run from at or cron (see the manual pages for crontab(5) or at(1) for more information) With a large cache of documents on the local disk, it can be very handy when traveling, or any other time the network connection is not active (a laptop with a dial-on-demand PPP connection, etc). Emacs/W3 can rely solely on its cache, and avoid checking to see if the page has changed on the remote server. In the case of a dial-on-demand PPP connection, this will keep the phone line free as long as possible, only bringing up the PPP connection when asking for a page that is not located in the cache. This is very useful for demonstrations as well. To turn this feature on, set the variable `url-standalone-mode' to non-`nil', or choose the `Use Cache Only' menu item (under `Options') File: w3.info, Node: Interfacing to Mail/News, Next: Debugging HTML, Prev: Disk Caching, Up: Advanced Features Interfacing to Mail/News ======================== More and more people are including URLs in their signatures, and within the body of mail messages. It can get quite tedious to type these into the minibuffer to follow one. With the latest versions of VM (the 5.9x series of betas) and Gnus (5.x), URLs are automatically highlighted, and can be followed with the mouse or the return key. How the URLs are viewed is determined by the variable `browse-url-browser-function', and it should be set to the symbol `browse-url-w3'. To access URLs from within RMAIL, the following hook should do the trick. (add-hook 'rmail-mode-hook (function (lambda () (define-key rmail-mode-map [mouse-2] 'w3-maybe-follow-link-mouse) (define-key rmail-mode-map "\r" 'w3-maybe-follow-link)))) File: w3.info, Node: Debugging HTML, Next: Hooks, Prev: Interfacing to Mail/News, Up: Advanced Features Debugging HTML ============== For those people that are adventurous, or are just as anal as I am about people writing valid HTML, set the variable `w3-debug-html' to `t' and see what happens. If a Emacs/W3 thinks it has encountered invalid HTML, then a debugging message is displayed. :: WORK :: Need to list the different values w3-debug-html can have, and :: WORK :: what they do :: File: w3.info, Node: Hooks, Next: Other Variables, Prev: Debugging HTML, Up: Advanced Features Hooks ===== These are the various hooks that can be used to customize some of Emacs/W3's behavior. They are arranged in the order in which they would happen when retrieving a document. These are all 'normal hooks' in standard Emacs-terminology, meaning they are functions (or lists of functions) that are called consecutively. `w3-load-hook' These hooks are run the first time a URL is fetched. All the Emacs/W3 variables are initialized before this hook is run. `w3-mode-hook' These hooks are run after a buffer has been parsed and displayed, but before any inlined images are downloaded and converted. `w3-source-file-hook' These hooks are run after displaying a document's source. File: w3.info, Node: Other Variables, Prev: Hooks, Up: Advanced Features Miscellaneous variables ======================= There are lots of variables that control the real nitty-gritty of Emacs/W3 that the beginning user probably shouldn't mess with. Here they are. `url-bad-port-list' List of ports to warn the user about connecting to. Defaults to just the mail and NNTP ports so a malicious HTML author cannot spoof mail or news to other people. `url-confirmation-func' What function to use for asking yes or no functions. Possible values are `'yes-or-no-p' or `'y-or-n-p', or any function that takes a single argument (the prompt), and returns `t' only if a positive answer is gotten. Defaults to `'yes-or-no-p'. `w3-default-action' A lisp symbol specifying what action to take for files with extensions that are not in the `mm-mime-extensions' assoc list. This is useful in case Emacs/W3 ever run across files with weird extensions (.foo, .README, .READMEFIRST, etc.). In most circumstances, this should not be required anymore. Possible values: any lisp symbol. Should be a function that takes no arguments. The return value does not matter, it is ignored. Some examples are `'w3-prepare-buffer' or `'indented-text-mode'. `w3-keep-old-buffers' Whether to keep old buffers around when following links. To avoid lots of buffers in one Emacs session, set this variable to `nil'. I recommend setting it to `t', so that backtracking from one link to another is faster. `url-passwd-entry-func' This is a symbol indicating which function to call to read in a password. If this variable is `nil' at startup, it is initialized depending on whether "EFS" or "ange-ftp" is being used. This function should accept the prompt string as its first argument, and the default value as its second argument. `w3-reuse-buffers' Determines what happens when `w3-fetch' is called on a document that has already been loaded into another buffer. Possible values are: `nil', `yes', and `no'. `nil' will ask the user if Emacs/W3 should reuse the buffer (this is the default value). A value of `yes' means assume the user wants to always reuse the buffer. A value of `no' means assume the user always wants to re-fetch the document. `w3-show-headers' This is a list of HTTP/1.0 headers to show at the end of a buffer. All the headers should be in lowercase. They are inserted at the end of the buffer in a <UL> list. Alternatively, if this is simply `t', then all the HTTP/1.0 headers are shown. The default value is `nil'. `w3-show-status, url-show-status' Whether to show progress messages in the minibuffer. `w3-show-status' controls if messages about the parsing are displayed, and `url-show-status' controls if a running total of the number of bytes transferred is displayed. These Can cause a large performance hit if using a remote X display over a slow link, or a terminal with a slow modem. `mm-content-transfer-encodings' An assoc list of CONTENT-TRANSFER-ENCODINGS or CONTENT-ENCODINGS and the appropriate decoding algorithms for each. If the `cdr' of a node is a list, then this specifies the decoder is an external program, with the program as the first item in the list, and the rest of the list specifying arguments to be passed on the command line. If using an external decoder, it must accept its input from `stdin' and send its output to `stdout'. If the `cdr' of a node is a symbol whose function definition is non-`nil', then that encoding can be handled internally. The function is called with 2 arguments, buffer positions bounding the region to be decoded. The function should completely replace that region with the unencoded information. Currently supported transfer encodings are: base64, x-gzip, 7bit, 8bit, binary, x-compress, x-hqx, and quoted-printable. `url-uncompressor-alist' An assoc list of file extensions and the appropriate uncompression programs for each. This is used to build the Accept-encoding header for HTTP/1.0 requests. File: w3.info, Node: More Help, Next: Future Directions, Prev: Advanced Features, Up: Top More Help ********* For more help on Emacs/W3, please send me mail (wmperry+w3@cs.indiana.edu). Several discussion lists have also been created for Emacs/W3. To subscribe, send mail to majordomo@indiana.edu, with the body of the message 'subscribe LISTNAME <EMAIL ADDRES>'. All other mail should go to <listname>@indiana.edu. * w3-announce - this list is for anyone interested in Emacs/W3, and should in general only be used by me. The gnu.emacs.sources newsgroup and a few other mailing lists are included on this. Please only use this list for major package releases related to Emacs/W3. (www-announce@w3.org is included on this list). * w3-beta - this list is for beta testers of Emacs/W3. These brave souls test out not-quite stable code. * w3-dev - a list consisting of myself and a few other people who are interested in the internals of Emacs/W3, and doing active development work. Pretty dead right now, but I hope it will grow. For more help on the World Wide Web in general, please refer to the comp.infosystems.www.* newsgroups. There are also several discussion lists concerning the Web. Send mail to <listname>-request@w3.org with a subject line of 'subscribe <listname>'. All mail should go to <listname>@w3.org. Administrative mail should go to www-admin@w3.org. The lists are: * www-talk - for general discussion of the World Wide Web, where its going, new features, etc. All the major developers are subscribed to this list. * www-announce - for announcements concerning the World Wide Web. Server changes, new servers, new software, etc. As a last resort, mail me. I'll try to answer as quickly as I can. File: w3.info, Node: Future Directions, Next: Reporting Bugs, Prev: More Help, Up: Top Future Directions ***************** Changes are constantly being made to the Emacs browser (hopefully all for the better). This is a list of the things that are being worked on right now. :: WORK :: Revamp the todo list File: w3.info, Node: Reporting Bugs, Next: Dealing with Firewalls, Prev: Future Directions, Up: Top Reporting Bugs ************** If any bugs are discovered in Emacs/W3, please report them to the mailing list w3-beta@indiana.edu - this is where the brave souls who beta test the latest versions of Emacs/W3 reside, and are generally very responsive to bug reports. Please make sure to use the bug submission feature of Emacs/W3, so that all relevant information will be sent along with your bug report. By default this is bound to the `<w>' key when in an Emacs/W3 buffer, or you can use <M-x w3-submit-bug> from anywhere within Emacs. For problems that are causing emacs to signal and error, please send a backtrace. You can get a backtrace by `M-x setvariable RET debug-on-error RET t RET', and then reproduce the error. If the problem is visual, please capture a copy of the output and mail it along with the bug report (preferably as a MIME attachment, but anything will do). You can use the `xwd' program under X-windows for this, or <Alt-PrintScreen> under Windows 95/NT. Sorry, but I don't remember what the magic incarnation is for doing a screen dump under NeXTstep or OS/2. If the problem is actually causing Emacs to crash, then you will need to also mail the maintainers of the various Emacs distributions with the bug. Please use the gnu.emacs.bug newgroup for reporting bugs with GNU Emacs 19, and comp.emacs.xemacs for reporting bugs with XEmacs 19 or XEmacs 20. I am actively involved with the beta testing of the latest versions of both branches of Emacs, and if I can reproduce the problem, I will do my best to see it gets fixed in the next release. It is also important to always maintain as much context as possible in your responses. I get so much email from my various Emacs-activities and work, that I cannot remember everything. If you send a bug report, and I send you a reply, and you reply with 'no that didn't work', then odds are I will have no clue what didn't work, much less what that was trying to fix in the first place. It will be much quicker and less painful if I don't have to waste a round-trip email exchange saying 'what are you talking about'. File: w3.info, Node: Dealing with Firewalls, Next: Proxy Gateways, Prev: Reporting Bugs, Up: Top Dealing with Firewalls ********************** By default, Emacs can support standard TCP/IP network connections on almost all the platforms it runs on (Unix, VMS, Windows, etc). However, there are several situations where it is not sufficient. Firewalls It is becoming more and more common to be behind a firewall or some other system that restricts your outbound network activity, especially if you are like me and away from the wonderful world of academia. Emacs/W3 has several different methods to get around firewalls (not to worry though - none of them should get you in trouble with the local MIS department.) Emacs cannot resolve hostnames. This happens quite often on SunOS workstations and some ULTRIX machines. Some C libraries do not include the hostname resolver routines in their static libraries. If Emacs was linked statically, and was not linked with the resolver libraries, it wil not be able to get to any machines off the local network. This is characterized by being able to reach someplace with a raw ip number, but not its hostname (`http://129.79.254.191/' works, but `http://www.cs.indiana.edu/' doesn't). The best solution for this problem is to recompile Emacs, making sure to either link dynamically (if available on your operating system), or include the `-lresolv'. If you do not have the disk space or the appropriate permissions to recompile Emacs, another alternative is using the `nslookup' program to do hostname resolution. To turn this on, set the variable `url-gateway-broken-resolution' in your `~/.emacs' file. This runs the program specified by `url-gateway-nslookup-program' (by default "`nslookup'" to do hostname resolution. This program should expect a single argument on the command line - the hostname to resolve, and should produce output similar to the standard Unix `nslookup' program: Name: www.cs.indiana.ed Address: 129.79.254.191 Using TERM (or TERM-like) Networking Software TERM (1) for slip-like access to the internet. NOTE: XEmacs and Emacs 19.22 or later have patches to enable native TERM networking. To enable it, `#define TERM' in the appropriate s/*.h file for the operating system, then change the `SYSTEM_LIBS' definition to include the `termnet' library that comes with the latest versions of TERM. If you run into any problems with the native TERM networking support in Emacs or XEmacs, please let wmperry+w3@cs.indiana.edu know, as he is responsible for the original support. Emacs/W3 has support for using the gateway mechanism for certain domains, and directly connecting to others. The variable `url-gateway-local-host-regexp' controls this behaviour. This is a regular expression (2) that matches local hosts that do not require the use of a gateway. If `nil', then all connections are made through the gateway. Emacs/W3 supports several methods of getting around gateways. The variable `url-gateway-method' controls which of these methods is used. This variable can have several values (use these as symbol names, not strings), ie: `(setq url-gateway-method 'telnet)'. Possible values are: "telnet" Use this method if you must first telnet and log into a gateway host, and then run telnet from that host to connect to outside machines. :: WORK :: document telnet gw variables This section needs more information, specifically documenting the following variables. For now, please do <C-h v> on the variable for more information. `url-gateway-telnet-host' `url-gateway-telnet-parameters' `url-gateway-telnet-password-prompt' `url-gateway-telnet-puser-name' `url-gateway-prompt-pattern' "rlogin" This method is identical to the `telnet' method, but uses `rlogin' to log into the remote machine without having to send the username and password over the wire every time. :: WORK :: document rlogin gw variables This section needs more information, specifically documenting the following variables. For now, please do <C-h v> on the variable for more information. `url-gateway-rlogin-host' `url-gateway-rlogin-parameters' `url-gateway-rlogin-user-name' `url-gateway-prompt-pattern' "tcp" Masanobu UMEDA (umerin@mse.kyutech.ac.jp) has written a very small application that you can run in a subprocess to do the network connections. "SOCKS" Use if the firewall has a SOCKS gateway running on it. :: WORK :: document socks variables This section needs more information, specifically documenting the following variables. For now, please do <C-h v> on the variable for more information. `socks-host' `socks-password' `socks-username' `socks-port' `socks-timeout' "native" This means that Emacs/W3 should use the builtin networking code of Emacs. This should be used only if there is no firewall, or the Emacs source has already been hacked to get around the firewall. Emacs/W3 should now be able to get outside the local network. If none of this makes sense, its probably my fault. Please check with the network administrators to see if they have a program that does most of this already, since somebody somewhere at the company has probably been through something similar to this before, and would be much more helpful/knowledgeable about the local setup than I would be. But feel free to mail me as a last resort. ---------- Footnotes ---------- (1) TERM is a user-level protocol for emulating IP over a serial line. More information is available at `ftp://sunsite.unc.edu/pub/Linux/apps/comm/term' (2) Please see the full Emacs distribution for a description of regular expressions File: w3.info, Node: Proxy Gateways, Next: Installing SSL, Prev: Dealing with Firewalls, Up: Top Proxy Gateways ************** In late January 1993, Kevin Altis and Lou Montulli proposed and implemented a new proxy service. This service requires the use of environment variables to specify a gateway server/port # to send protocol requests to. Each protocol (HTTP, WAIS, gopher, FTP, etc.) can have a different gateway server. The environment variables are `PROTOCOL'_proxy, where `PROTOCOL' is one of the supported network protocols (gopher, file, HTTP, FTP, etc.) For companies with internal intranets, it will usually be helpful to define a list of hosts that should be contacted directly, not sent through the proxy. The `NO_PROXY' environment variable controls what hosts are able to be contacted directly. This should be a comma separated list of hostnames, domain names, or a mixture of both. Asterisks can be used as a wildcard. For example: NO_PROXY=*.aventail.com,home.com,*.seanet.com tells Emacs/W3 to contact all machines in the aventail.com and seanet.com domains directly, as well as the machine named home.com. For those adventurous souls who enjoy writing regular expressions, all the proxy settings can be manipulated from Emacs-Lisp. The variable `url-proxy-services' controls this. This is an assoc list, keyed on the protocol type (HTTP, gopher, etc) in all lowercase. The `cdr' of each entry should be the ADDRESS of the proxy server to contact, followed by ":" and the port number to use. In the case of the special "no_proxy" entry, it should be a regular expression that matches any hostnames that should be contacted directly. (setq url-proxy-services '(("http" . "proxy.aventail.com:80") ("no_proxy" . "^.*\\(aventail\\|seanet\\)\.com"))) File: w3.info, Node: Installing SSL, Next: Mailcap Files, Prev: Proxy Gateways, Up: Top Installing SSL ************** In order to use SSL in Emacs/W3, an implementation of SSL is necessary. Emacs/W3 is configued to work out of the box with SSLeay 0.6.6 or later. For best results, you should apply a patch that makes the SSLeay client much quieter about what it reports. You can download SSLeay from `ftp://ftp.psy.uq.oz.au/pub/Crypto/SSL/' The following variables control how the external program is invoked. `ssl-program-name' The name of the program to run, as a string. (setq ssl-program-name "s_client") `ssl-program-arguments' This should be used if your SSL program needs command line switches to specify any behaviour (certificate file locations, etc). This is a list of strings and symbols. The special symbols 'host and 'port may be used in the list of arguments and will be replaced with the hostname and service/port that will be connected to. (setq ssl-program-arguments '("-host" host "-port" service "-verify" "4" "-CApath /usr/local/ssl/certs")) File: w3.info, Node: Mailcap Files, Next: Down with DoubleClick, Prev: Installing SSL, Up: Top Mailcap Files ************* NCSA Mosaic and almost all other WWW browsers rely on a separate file for mapping MIME types to external viewing programs. This takes some of the burden off of browser developers, so each browser does not have to support all image formats, or postscript, etc. Instead of having the users of Emacs/W3 duplicate this in lisp, this file can be parsed using the `mm-parse-mailcaps' function. This function is called each time Emacs/W3 is loaded. It tries to locate mimetype files in several places. If the environment variable `MAILCAPS' is nonempty, then this is assumed to specify a UNIX-like path of mimetype files (this is a colon separated string of pathnames). If the `MAILCAPS' environment variable is empty, then Emacs/W3 looks for these files: 1. `~/.mailcap' 2. `/etc/mailcap' 3. `/usr/etc/mailcap' 4. `/usr/local/etc/mailcap' This format of this file is specified in RFC 1343, but a brief synopsis follows (this is taken verbatim from sections of RFC 1343). Each mailcap file consists of a set of entries that describe the proper handling of one media type at the local site. For example, one line might tell how to display a message in Group III fax format. A mailcap file consists of a sequence of such individual entries, separated by newlines (according to the operating system's newline conventions). Blank lines and lines that start with the "#" character (ASCII 35) are considered comments, and are ignored. Long entries may be continued on multiple lines if each non-terminal line ends with a backslash character ('\', ASCII 92), in which case the multiple lines are to be treated as a single mailcap entry. Note that for such "continued" lines, the backslash must be the last character on the line to be continued. Each mailcap entry consists of a number of fields, separated by semi-colons. The first two fields are required, and must occur in the specified order. The remaining fields are optional, and may appear in any order. The first field is the content-type, which indicates the type of data this mailcap entry describes how to handle. It is to be matched against the type/subtype specification in the "Content-Type" header field of an Internet mail message. If the subtype is specified as "*", it is intended to match all subtypes of the named content-type. The second field, view-command, is a specification of how the message or body part can be viewed at the local site. Although the syntax of this field is fully specified, the semantics of program execution are necessarily somewhat operating system dependent. The optional fields, which may be given in any order, are as follows: * The "compose" field may be used to specify a program that can be used to compose a new body or body part in the given format. Its intended use is to support mail composing agents that support the composition of multiple types of mail using external composing agents. As with the view- command, the semantics of program execution are operating system dependent. The result of the composing program may be data that is not yet suitable for mail transport--that is, a Content-Transfer-Encoding may need to be applied to the data. * The "composetyped" field is similar to the "compose" field, but is to be used when the composing program needs to specify the Content-type header field to be applied to the composed data. The "compose" field is simpler, and is preferred for use with existing (non-mail-oriented) programs for composing data in a given format. The "composetyped" field is necessary when the Content-type information must include auxilliary parameters, and the composition program must then know enough about mail formats to produce output that includes the mail type information. * The "edit" field may be used to specify a program that can be used to edit a body or body part in the given format. In many cases, it may be identical in content to the "compose" field, and shares the operating-system dependent semantics for program execution. * The "print" field may be used to specify a program that can be used to print a message or body part in the given format. As with the view-command, the semantics of program execution are operating system dependent. * The "test" field may be used to test some external condition (e.g. the machine architecture, or the window system in use) to determine whether or not the mailcap line applies. It specifies a program to be run to test some condition. The semantics of execution and of the value returned by the test program are operating system dependent. If the test fails, a subsequent mailcap entry should be sought. Multiple test fields are not permitted--since a test can call a program, it can already be arbitrarily complex. * The "needsterminal" field indicates that the view-command must be run on an interactive terminal. This is needed to inform window-oriented user agents that an interactive terminal is needed. (The decision is not left exclusively to the view-command because in some circumstances it may not be possible for such programs to tell whether or not they are on interactive terminals.) The needsterminal command should be assumed to apply to the compose and edit commands, too, if they exist. Note that this is NOT a test--it is a requirement for the environment in which the program will be executed, and should typically cause the creation of a terminal window when not executed on either a real terminal or a terminal window. * The "copiousoutput" field indicates that the output from the view-command will be an extended stream of output, and is to be interpreted as advice to the UA (User Agent mail- reading program) that the output should be either paged or made scrollable. Note that it is probably a mistake if needsterminal and copiousoutput are both specified. * The "description" field simply provides a textual description, optionally quoted, that describes the type of data, to be used optionally by mail readers that wish to describe the data before offering to display it. * The "x11-bitmap" field names a file, in X11 bitmap (xbm) format, which points to an appropriate icon to be used to visually denote the presence of this kind of data. * Any other fields beginning with "x-" may be included for local or mailer-specific extensions of this format. Implementations should simply ignore all such unrecognized fields to permit such extensions, some of which might be standardized in a future version of this document. File: w3.info, Node: Down with DoubleClick, Next: General Index, Prev: Mailcap Files, Up: Top Down with DoubleClick ********************* :: WORK :: Document why doubleclick is evil :: WORK :: Document how you can never see another ad from them again File: w3.info, Node: General Index, Next: Key Index, Prev: Down with DoubleClick, Up: Top General Index ************* * Menu: * 32-Bit Windows: Windows. * Authentication, Basic: Security. * Authentication, Digest: Security. * AXP-VMS: VMS. * Bad HTML: Debugging HTML. * Basic Usage: Basic Usage. * Broken SunOS libc: Dealing with Firewalls. * browse-url-browser-function: Interfacing to Mail/News. * Browser emulation: Emulation. * Browsing with no network connection: Disk Caching. * Buffer movement: Action. * Bugs: Reporting Bugs. * Cache cleaning: Disk Caching. * Cache only mode: Disk Caching. * Caching: Disk Caching. * Cleaning the cache: Disk Caching. * Clearing the cache: Disk Caching. * Clueless in Seattle: Getting Started. * Completion of URLs: Global History. * Contacting the author: Reporting Bugs. * Debugging: Debugging HTML. * Default stylesheet: Startup Files. * Digital VMS: VMS. * Disk Cache: Disk Caching. * DOS: MS-DOS. * Emulation of other browsers: Emulation. * Export Restrictions <1>: Installing SSL. * Export Restrictions: Security. * Exportability <1>: Installing SSL. * Exportability: Security. * Faulty hostname resolvers: Dealing with Firewalls. * Firewalls: Dealing with Firewalls. * Gag Puke Retch <1>: Installing SSL. * Gag Puke Retch: Security. * Getting Started: Getting Started. * GNUS: Interfacing to Mail/News. * History Lists: Session History. * Hooks: Hooks. * Hostname resolution: Dealing with Firewalls. * HTTP Proxy: Proxy Gateways. * HTTP/1.0 Authentication <1>: Installing SSL. * HTTP/1.0 Authentication: Security. * Interfacing to Mail/News: Interfacing to Mail/News. * Invalid HTML: Debugging HTML. * Limiting the size of the cache: Disk Caching. * lpr-buffer: Miscellaneous. * lpr-command: Miscellaneous. * lpr-switches: Miscellaneous. * Lynx emulation: Emulation. * Microsloth <1>: Windows. * Microsloth: MS-DOS. * mime-types file: Adding MIME types based on file extensions. * mm-add-mailcap-entry: Specifying Viewers. * mm-content-transfer-encodings: Other Variables. * mm-mime-extensions: Adding MIME types based on file extensions. * mm-parse-mimetypes: Adding MIME types based on file extensions. * MS-DOG: MS-DOS. * MS-DOS: MS-DOS. * Netless browsing: Disk Caching. * Netscape emulation: Emulation. * Newsgroups: More Help. * No Proxy: Proxy Gateways. * NO_PROXY: Proxy Gateways. * Non-Unix Operating Systems: Non-Unix Operating Systems. * OS/2: OS/2. * Paranoia: Security. * Persistent Cache: Disk Caching. * Preferences: Preferences Panel. * Proxies: Proxy Gateways. * Proxies, environment variables: Proxy Gateways. * Proxies, exclusion lists: Proxy Gateways. * Proxies, setting from lisp: Proxy Gateways. * Proxy Servers: Proxy Gateways. * Relevant Newsgroups: More Help. * Relying on cache: Disk Caching. * Reporting Bugs: Reporting Bugs. * RMAIL: Interfacing to Mail/News. * scroll-down: Movement. * Secure Sockets Layer <1>: Installing SSL. * Secure Sockets Layer: Security. * Security: Security. * Security, Basic: Security. * Security, Digest: Security. * SSL <1>: Installing SSL. * SSL: Security. * ssl-program-arguments: Installing SSL. * ssl-program-name: Installing SSL. * Standalone mode: Disk Caching. * Startup files: Startup Files. * Support: More Help. * TERM: Dealing with Firewalls. * turn-on-lynx-emulation: Emulation. * turn-on-netscape-emulation: Emulation. * Turning on caching: Disk Caching. * url-automatic-caching: Disk Caching. * url-bad-port-list: Other Variables. * url-confirmation-func: Other Variables. * url-gateway-broken-resolution: Dealing with Firewalls. * url-gateway-local-host-regexp: Dealing with Firewalls. * url-gateway-method: Dealing with Firewalls. * url-global-history-file: Global History. * url-keep-history <1>: Global History. * url-keep-history: Session History. * url-passwd-entry-func: Other Variables. * url-proxy-services: Proxy Gateways. * url-show-status: Other Variables. * url-standalone-mode: Disk Caching. * url-uncompressor-alist: Other Variables. * url-use-hypertext-dired: Action. * url-view-url: Information. * Usefulness of global history: Global History. * Using Emacs/W3 with Gnus: Interfacing to Mail/News. * Using Emacs/W3 with RMAIL: Interfacing to Mail/News. * Using Emacs/W3 with VM: Interfacing to Mail/News. * VAX-VMS: VMS. * VM: Interfacing to Mail/News. * VMS: VMS. * w3: Getting Started. * w3-backward-in-history <1>: Session History. * w3-backward-in-history <2>: Action. * w3-backward-in-history: Movement. * w3-complete-link: Action. * w3-debug-buffer: Debugging HTML. * w3-debug-html: Debugging HTML. * w3-default-action: Other Variables. * w3-default-homepage: Getting Started. * w3-document-information: Information. * w3-document-information-this-url: Information. * w3-end-of-document: Movement. * w3-fetch <1>: Session History. * w3-fetch: Action. * w3-follow-inlined-image: Action. * w3-follow-link: Action. * w3-follow-mouse: Action. * w3-forward-in-history <1>: Session History. * w3-forward-in-history <2>: Action. * w3-forward-in-history: Movement. * w3-goto-last-buffer <1>: Action. * w3-goto-last-buffer: Movement. * w3-hotlist-add-document: Hotlist Handling. * w3-hotlist-append: Hotlist Handling. * w3-hotlist-apropos: Hotlist Handling. * w3-hotlist-delete: Hotlist Handling. * w3-hotlist-file: Hotlist Handling. * w3-hotlist-refresh: Hotlist Handling. * w3-hotlist-rename-entry: Hotlist Handling. * w3-insert-formatted-url: Miscellaneous. * w3-insert-this-url: Miscellaneous. * w3-keep-history: Action. * w3-keep-old-buffers: Other Variables. * w3-latex-docstyle: Miscellaneous. * w3-latex-packages: Miscellaneous. * w3-latex-print-links: Miscellaneous. * w3-latex-use-latex2e: Miscellaneous. * w3-latex-use-maketitle: Miscellaneous. * w3-leave-buffer <1>: Action. * w3-leave-buffer: Movement. * w3-load-hook: Hooks. * w3-lynx-emulation-minor-mode: Emulation. * w3-mail-current-document: Miscellaneous. * w3-mail-document-under-point: Miscellaneous. * w3-mode-hook: Emulation. * w3-netscape-emulation-minor-mode: Emulation. * w3-open-local: Action. * w3-print-commnad: Miscellaneous. * w3-print-this-url <1>: Miscellaneous. * w3-print-this-url: Action. * w3-print-url-under-point <1>: Miscellaneous. * w3-print-url-under-point: Action. * w3-quit <1>: Action. * w3-quit: Movement. * w3-reload-document: Action. * w3-reuse-buffers: Other Variables. * w3-save-as: Action. * w3-save-this-url: Information. * w3-save-url: Information. * w3-scroll-up: Movement. * w3-show-headers: Other Variables. * w3-show-history: Session History. * w3-show-history-list: Action. * w3-show-hotlist: Hotlist Handling. * w3-show-status: Other Variables. * w3-source-document: Information. * w3-source-document-at-point: Information. * w3-start-of-document: Movement. * w3-use-hotlist: Hotlist Handling. * w3-use-links: Miscellaneous. * w3-view-this-url: Information. * w3-widget-backward: Movement. * w3-widget-forward: Movement. * Warp: OS/2. * Windows '95: Windows. * Windows (32-Bit): Windows.