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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: Top, Next: Getting Started, Prev: (dir), Up: (dir)
W3
**
Users can browse the World Wide Web from within Emacs by using
Emacs/W3. All of the widely used (and even some not very widely used)
URL schemes are supported, and it is very easy to add new methods as the
need arises.
Emacs/W3 provides some core functionality that can be readily re-used
from any program in Emacs. Users and other package writers are
encouraged to Web-enable their applications and daily work routines
with the library.
Emacs/W3 is completely customizable, both from Emacs-Lisp and from
stylesheets *Note Stylesheets:: If there is any aspect of Emacs/W3 that
cannot be modified to your satisfaction, please send mail to the
w3-beta@indiana.edu mailing list with any suggestions. *Note Reporting
Bugs::
This manual corresponds to Emacs/W3 v4.0pre.7
* Menu:
* Getting Started:: Getting up and running with Emacs/W3
* Basic Usage:: Basic movement and usage of Emacs/W3.
* Compatibility:: Explanation of compatibility with
other browsers.
* Stylesheets:: How to control the look of web pages
* Supported URLs:: What URL schemes are supported.
* MIME Support:: Support for MIME
* Security:: Various security methods supported
* Non-Unix Operating Systems:: Special considerations necessary to get
up and running correctly under non-unix
OS's.
* Speech Integration:: Outputting to a speech synthesizer.
* Advanced Features:: Some of the more arcane features.
* More Help:: How to get more help--mailing lists,
newsgroups, etc.
* Future Directions:: Plans for future revisions
Appendices:
* Reporting Bugs:: How to report a bug in Emacs/W3.
* Dealing with Firewalls:: How to get around your firewall.
* Proxy Gateways:: Using a proxy gateway with Emacs/W3.
* Installing SSL:: Turning on SSL support.
* Mailcap Files:: An explanation of Mailcap files.
* Down with DoubleClick:: Annoyed by advertisements? Read this!
Indices:
* General Index:: General Index.
* Key Index:: Menus of command keys and their references.
File: w3.info, Node: Getting Started, Next: Basic Usage, Prev: Top, Up: Top
Getting Started
***************
If installed correctly, starting Emacs/W3 is quite painless. Just
type `M-x w3' in a running Emacs session. This will retrieve the
default page that has been configured (*note Preferences Panel::.) - by
default the documentation for Emacs/W3 at Indiana University.
If the default page is not retrieved correctly at startup, you will
have to do some customization (*note Preferences Panel::.).
Once started, you can use the mouse and the menu or use the following
key commands (for more commands and more detail, *note Basic Usage:
Basic Usage.).
move forward
press the space bar,
move backwards
press the backspace key,
move to the next HTML reference on the page
press the `TAB' key,
move to the previous HTML reference on the page
press the `SHIFT' and `TAB' keys at the same time. If this does
not work (some text terminals cannot distinguish between `TAB' and
`SHIFT-TAB', pressing the `ALT' and `TAB' keys should also work.
follow a link
put the cursor over it and press the `RETURN' key, or
click the left mouse button on it,
fetch a URL
press the `Control' and `o' keys at the same time,
type the URL, and then press the `RETURN' key,
return to the last URL you were at
press the `l' key,
quit W3 mode
press the `q' key.
* Menu:
* Downloading:: Where to download Emacs/W3.
* Building and Installing:: Compiling and installing from source.
* Startup Files:: What is where, and why.
* Preferences Panel:: Quick configuration of common options.
File: w3.info, Node: Downloading, Next: Building and Installing, Prev: Getting Started, Up: Getting Started
Downloading
===========
:: WORK :: What you need, and why
:: WORK :: Where to download Emacs, XEmacs, various platforms
:: WORK :: Where to download Emacs/W3
:: WORK :: Where to download related utilities (netpbm, xv, gimp, etc.)
File: w3.info, Node: Building and Installing, Next: Startup Files, Prev: Downloading, Up: Getting Started
Building and Installing
=======================
:: WORK :: Document makefile variables
:: WORK :: Document what gets installed where, why
File: w3.info, Node: Startup Files, Next: Preferences Panel, Prev: Building and Installing, Up: Getting Started
Startup Files
=============
:: WORK :: startup files
This section should document where Emacs/W3 looks for its startup files,
and what each one does. 'profile' 'stylesheet' 'hotlist' 'history' etc.
File: w3.info, Node: Preferences Panel, Prev: Startup Files, Up: Getting Started
Preferences Panel
=================
:: WORK :: pref panel
This should document the quick preferences panel. M-x
w3-preferences-edit
File: w3.info, Node: Basic Usage, Next: Compatibility, Prev: Getting Started, Up: Top
Basic Usage
***********
Emacs/W3 is similar to the Info package all Emacs users hold near and
dear to their hearts (*Note Info: (info)Top, for a description of
Info). Basically, `space' and `backspace' control scrolling, and
`return' or the middle mouse button follows a hypertext link. The
`tab' and `Meta-tab' keys maneuver around the various links on the page.
NOTE: Starting with Emacs/W3 4.0, form entry areas in a page can be
typed directly into. This is one of the main differences in navigation
from version 2.0. If you are used to using the `f' and `b' keys to
navigate around a buffer, I suggest training yourself to always use
`tab' and `M-tab' - it will save time and frustration on pages with
lots of form fields.
By default, hypertext links are surrounded by '[[' and ']]' on
non-graphic terminals (VT100, DOS window, etc.). On a graphics
terminal, the links are in shown in different colors. *Note
Stylesheets:: for information on how to change this.
There are approximately 50 keys bound to special Emacs/W3 functions.
The basic rule of thumb regarding keybindings in Emacs/W3 is that a
lowercase key takes an action on the current document, and an uppercase
key takes an action on the document pointed to by the hypertext link
under the cursor.
There are several areas that the keybindings fall into: movement,
information, action, and miscellaneous.
* Menu:
* Movement:: Moving around in the buffer.
* Information:: Getting information about a document.
* Action:: Following links, printing, etc.
* Miscellaneous:: Everything else.
File: w3.info, Node: Movement, Next: Information, Prev: Basic Usage, Up: Basic Usage
Movement
========
All the standard Emacs bindings for movement are still in effect,
with a few additions for convenience.
`space'
Scroll downward in the buffer. With prefix arg, scroll down that
many screenfuls.
`backspace'
Scroll upward in the buffer. With prefix arg, scroll up that many
screenfuls.
`<'
Goes to the start of document
`>'
Goes to the end of document
`Meta-tab, Shift-tab, b'
Attempts to move backward one link area in the current document.
Signals an error if no previous links are found.
`tab, f, n'
Attempts to move forward one link area in the current document.
Signals an error if no more links are found.
`B'
Move backwards in the history stack.
`F'
Move forwards in the history stack.
`l'
Return to the last buffer shown before this buffer.
`q'
Kill this buffer.
`Q, u'
Bury this buffer, but don't kill it
File: w3.info, Node: Information, Next: Action, Prev: Movement, Up: Basic Usage
Information
===========
These functions relate information about one or more links on the
current document.
`v'
This shows the URL of the current document in the minibuffer.
`V'
This shows the URL of the hypertext link under point in the
minibuffer.
`i'
Shows miscellaneous information about the currently displayed
document. This includes the URL, the last modified date, MIME
headers, the HTTP response code, and any relationships to other
documents. Any security information is also displayed.
`I'
Shows information about the URL at point.
`s'
This shows the HTML source of the current document in a separate
buffer. The buffer's name is based on the document's URL.
`S'
Shows the HTML source of the hypertext link under point in a
separate buffer. The buffer's name is based on the document's URL.
`k'
This stores the current document's URL in the kill ring, and also
in the current window-system's clipboard, if possible.
`K'
Stores the URL of the document under point in the kill ring, and
also in the current window-system's clipboard, if possible.
File: w3.info, Node: Action, Next: Miscellaneous, Prev: Information, Up: Basic Usage
Action
======
First, here are the keys and functions that bring up a new hypertext
page, usually creating a new buffer.
`m'
Choose a link from the current buffer and follow it. A
completing-read is done on all the links, so `space' and `TAB' can
be used for completion.
`return'
Pressing return when over a hyperlink attempts to follow the link
under the cursor. With a prefix argument (`C-u'), this forces the
file to be saved to disk instead of being passed off to other
viewers or being parsed as HTML.
Pressing return when over a form input field can cause
auto-submission of the form. This is for Mosaic and Netscape
compatibility. If there is only one item in the form other than
submit or reset buttons, then the form will be submitted.
`Middle Mouse Button'
Attempt to follow a hypertext link under the mouse cursor.
Clicking on a form input field will prompt in the minibuffer for
the data to insert into the input field. Type checking is done,
and the data is only entered into the form when data of the
correct type is entered (ie: cannot enter 44 for 'date' field,
etc).
`Control Middle Mouse Button, Meta return'
Tries to retrieve the inlined image that is under point. It
ignores any form entry areas or hyperlinks, and blindly follows
any inlined image. Useful for seeing images that are meant to be
used as hyperlinks when not on a terminal capable of displaying
graphics.
`p'
Prints out the current buffer in a variety of formats, including
PostScript, HTML source, or formatted text.
`P'
Prints out the URL under point in a variety of formats, including
PostScript, HTML source, or formatted text.
`m'
Selects a destination from a list of all the hyperlinks in the
current buffer. Use `space' and `tab' to complete on the links.
`r, g'
Reloads the current document. The position within the buffer
remains the same (unless the document has changed since it was
last retrieved, in which case it should be relatively close).
This causes an unconditional reload from the remote server - the
locally cached copy is not consulted.
`C-o'
Prompts for a URL in the minibuffer, and attempts to fetch it. If
there are any errors, or Emacs/W3 cannot understand the type of
link requested, the errors are displayed in a hypertext buffer.
`o'
Opens a local file, interactively. This prompts for a local file
name to open. The file must exist, and may be a directory. If
the requested file is a directory and `url-use-hypertext-dired' is
`nil', then a dired-mode buffer is displayed. If non`nil', then
Emacs/W3 automatically generates a hypertext listing of the
directory. The hypertext mode is the default, so that all the
keys and functions remain the same.
`M-s'
Save a document to the local disk as HTML Source, Formatted Text,
LaTeX Source, or Binary.
`Hv'
If `url-keep-history' is non-`nil', then Emacs/W3 keeps track of
all the URLs visited in an Emacs session. This function takes all
the links that are in that internal list, and formats them as
hypertext links in a list.
And here are the commands to move around between Emacs/W3 buffers:
`l'
Goes to the last WWW buffer seen.
`q'
Quits WWW mode. This kills the current buffer and goes to the most
recently visited buffer.
`u'
This is similar to w3-quit, but the buffer is not killed, it is
moved to the bottom of the buffer list (so it is the least likely
to show up as the default with switch-to-buffer). This is
different from `w3-goto-last-buffer' in that it does not return to
the last WWW page visited - it is the same as using
`switch-to-buffer' - the buffer left in the window is fairly
random.
`HB, B'
Takes one step back along the path in the current history. Has no
effect if at the beginning of the session history.
`HF, F'
Takes one step forward along the path in the current history. Has
no effect if at the end of the session history.
File: w3.info, Node: Miscellaneous, Prev: Action, Up: Basic Usage
Miscellaneous
=============
`M-m'
Mails the current document to someone. Choose from several
different formats to mail: formatted text, HTML source,
PostScript, or LaTeX source. When the HTML source is mailed, then
an appropriate <base> tag is inserted at the beginning of the
document so that relative links may be followed correctly by
whoever receives the mail.
`M-M'
Mails the document pointed to by the hypertext link under point to
someone. Choose from several different formats to mail: formatted
text, HTML source, PostScript, or LaTeX source. When the HTML
source is mailed, then an appropriate <base> tag is inserted at
the beginning of the document so that relative links may be
followed correctly by whoever receives the mail.
`p'
Prints the current document. Choose from several different
formats to print: formatted text, HTML source, PostScript (with
ps-print), or by using LaTeX and dvips).
When the formatted text is printed, the normal `lpr-buffer'
function is called, and the variables `lpr-command' and
`lpr-switches' control how the document is printed.
When the HTML source is printed, then an appropriate <base> tag is
inserted at the beginning of the document. When postscript is
printed, then the HTML source of the document is converted into
LaTeX source. There are several variables controlling what the
final LaTeX document looks like.
:: WORK :: Document the new LaTeX backend
`w3-latex-use-latex2e'
If non-`nil', configures the LaTeX engine to use the LaTeX2e
syntax. A `nil' value indicates that LaTeX 2.0.9
compabibility will be used instead.
`w3-latex-docstyle'
The document style to use when printing or mailing converted
HTML files in LaTeX. Good defaults are: {article},
[psfig,twocolumn]{article}, etc.
`w3-latex-packages'
List of LaTeX packages to include. Currently this is only
used if `w3-latex-use-latex2e' is non-`nil'.
`w3-latex-use-maketitle'
If non-`nil', the LaTeX engine will use real LaTeX title
pages for document titles.
`w3-latex-print-links'
If non-`nil', prints the URLs of hypertext links as endnotes
at the end of the document. If set to `footnote', prints the
URL's as footnotes on each page.
`P'
Prints the document pointed to by the hypertext link under point.
Please see the previous item for more information.
`M-x w3-insert-formatted-url'
Insert a fully formatted HTML link into another buffer. This gets
the name and URL of either the current buffer, or, with a prefix
arg, of the link under point, and construct the appropriate
<a...>...</a> markup and insert it into the desired buffer.
`M-tab'
Inserts the URL of the current document into another buffer.
Buffer is prompted for in the minibuffer. With prefix arg, uses
the URL of the link under point.
`U'
Selects one of the <LINK> tags from this document and fetch it.
Links are attributes of a specific document, and can tell such
things as who made the document, where a table of contents is
located, etc.
Link tags specify relationships between documents in two ways.
Normal (forward) relationships (where the link has a REL="xxx"
attribute), and reverse relationships (where the link has a
REV="xxx" attribute). This first asks what type of link to follow
(Normal or Reverse), then does a `completing-read' on only the
links that have that type of relationship.
File: w3.info, Node: Compatibility, Next: Stylesheets, Prev: Basic Usage, Up: Top
Compatibility with other Browsers
*********************************
Due to the popularity of several other browsers, Emacs/W3 offers an
easy transition to its much better way of life. This ranges from being
able to share the same preferences files and disk cache to actually
emulating the keybindings used in other browsers.
* Menu:
* Emulation:: Emacs/W3 can emulate the keybindings and
other behaviours of other browsers.
* Hotlist Handling:: A hotlist is an easy way to keep track of
interesting Web pages without having to
remember the exact path to get there.
* Session History:: Keeping a history of documents visited
in one Emacs sessions allows the use of
'forward' and 'back' buttons easily.
* Global History:: Keeping a history of all the places ever
visited on the web.
File: w3.info, Node: Emulation, Next: Hotlist Handling, Prev: Compatibility, Up: Compatibility
Emulation
=========
:: WORK :: Document lynx emulation
`Down arrow'
Highlight next topic
`Up arrow'
Highlight previous topic
`Right arrow, Return, Enter'
Jump to highlighted topic
`Left arrow'
Return to previous topic
`+'
Scroll down to next page (Page-Down)
`-'
Scroll up to previous page (Page-Up)
`SPACE'
Scroll down to next page (Page-Down)
`b'
Scroll up to previous page (Page-Up)
`C-A'
Go to first page of the current document (Home)
`C-E'
Go to last page of the current document (End)
`C-B'
Scroll up to previous page (Page-Up)
`C-F'
Scroll down to next page (Page-Down)
`C-N'
Go forward two lines in the current document
`C-P'
Go back two lines in the current document
`)'
Go forward half a page in the current document
`('
Go back half a page in the current document
`#'
Go to Toolbar or Banner in the current document
`?, h'
Help (this screen)
`a'
Add the current link to a bookmark file
`c'
Send a comment to the document owner
`d'
Download the current link
`e'
Edit the current file
`g'
Goto a user specified URL or file
`i'
Show an index of documents
`j'
Execute a jump operation
`k'
Show a list of key mappings
`l'
List references (links) in current document
`m'
Return to main screen
`o'
Set your options
`p'
Print the current document
`q'
Quit
`/'
Search for a string within the current document
`s'
Enter a search string for an external search
`n'
Go to the next search string
`v'
View a bookmark file
`V'
Go to the Visited Links Page
`x'
Force submission of form or link with no-cache
`z'
Cancel transfer in progress
`[backspace]'
Go to the history Page
`='
Show file and link info
`\'
Toggle document source/rendered view
`!'
Spawn your default shell
`*'
Toggle image_links mode on and off
`['
Toggle pseudo_inlines mode on and off
`]'
Send an HTTP HEAD request for the current doc or link
`C-R'
Reload current file and refresh the screen
`C-W'
Refresh the screen
`C-U'
Erase input line
`C-G'
Cancel input or transfer
`C-T'
Toggle trace mode on and off
`C-K'
Invoke the Cookie Jar Page
:: WORK :: Document netscape emulation
Uh, turn this into pretty tables about what keys are emulated.
(define-key w3-netscape-emulation-minor-mode-map "\M-s" 'w3-save-as)
(define-key w3-netscape-emulation-minor-mode-map "\M-m" 'w3-mailto)
(define-key w3-netscape-emulation-minor-mode-map "\M-n" 'make-frame)
(define-key w3-netscape-emulation-minor-mode-map "\M-l" 'w3-fetch)
(define-key w3-netscape-emulation-minor-mode-map "\M-o" 'w3-open-local)
(define-key w3-netscape-emulation-minor-mode-map "\M-p" 'w3-print-this-url)
(define-key w3-netscape-emulation-minor-mode-map "\M-q" 'w3-quit)
(define-key w3-netscape-emulation-minor-mode-map "\M-f" 'w3-search-forward)
(define-key w3-netscape-emulation-minor-mode-map "\M-g" 'w3-search-again)
(define-key w3-netscape-emulation-minor-mode-map "\M-r" 'w3-reload-document)
(define-key w3-netscape-emulation-minor-mode-map "\M-i" 'w3-load-delayed-images)
(define-key w3-netscape-emulation-minor-mode-map "\M-a" 'w3-hotlist-add-document)
(define-key w3-netscape-emulation-minor-mode-map "\M-b" 'w3-show-hotlist)
(define-key w3-netscape-emulation-minor-mode-map "\M-h" 'w3-show-history-list)
File: w3.info, Node: Hotlist Handling, Next: Session History, Prev: Emulation, Up: Compatibility
Hotlist Handling
================
:: WORK :: Document that it supports different types of hotlist
formats
:: WORK :: Make sure everything hotlist related can be accessed via 'h'
In order to avoid having to traverse many documents to get to the same
document over and over, Emacs/W3 supports a "hotlist" like Mosaic.
This is a file that contains URLs and aliases. Hotlists allow quick
access to any document in the Web, providing it has been visited and
added to the hotlist. The variable `w3-hotlist-file' determines where
this information is saved. The structure of the file is compatible
with Mosaic's hotlist file, so this defaults to
`~/.mosaic-hotlist-default'.
Hotlist commands are:
`a'
Adds the current document to the hotlist, with the buffer name as
its identifier. Modifies the file specified by `w3-hotlist-file'.
If this is given a prefix-argument (via `C-u'), the title is
prompted for instead of automatically defaulting to the document
title.
`hR'
This rereads the default hostlist file specified by
`w3-hotlist-file'.
`d'
Prompts for the alias of the entry to kill. Pressing the spacebar
or tab will list out partial completions. The internal
representation of the hotlist and the file specified by
`w3-hotlist-file' are updated.
`hr'
Some hotlist item names can be very unwieldy (`Mosaic for X level
2 fill out form support'), or uninformative (`Index of /').
Prompts for the item to rename in the minibuffer--use the spacebar
or tab key for completion. After having chosen an item to rename,
prompts for a new title until a unique title is entered. Modifies
the file specified by `w3-hotlist-file'.
`hu'
Prompts for the alias to jump to. Pressing the <spacebar> or
<tab> key shows partial completions.
`hv'
Converts the hotlist into HTML and displays it.
`ha'
Shows the hotlist entries matching a regular expression.
`hA'
Appends another hotlist file to the one currently in memory.
File: w3.info, Node: Session History, Next: Global History, Prev: Hotlist Handling, Up: Compatibility
History
=======
Almost all web browsers keep track of the URLs followed from a page,
so that it can provide forward and back buttons to keep a path of URLs
that can be traversed easily.
If the variable `url-keep-history' is `t', then Emacs/W3 keeps a
list of all the URLs visited in a session.
To view a listing of the history for this session of Emacs/W3, use
`M-x w3-show-history' from any buffer, and Emacs/W3 generates an HTML
document showing every URL visited since Emacs started (or cleared the
history list), and then format it. Any of the links can be chosen and
followed to the original document. To clear the history list, choose
'Clear History' from the 'Options' menu.
Another twist on the history list mechanism is the fact that all
Emacs/W3 buffers remember what URL, buffer, and buffer position of the
last document, and also keeps track of the next location jumped to from
that buffer. This means that the user can go forwards and backwards
very easily along the path taken to reach a particular document. To go
forward, use the function `w3-forward-in-history', to go backward, use
the function `w3-backward-in-history'.
File: w3.info, Node: Global History, Prev: Session History, Up: Compatibility
Global History
==============
:: WORK :: Document that the global history can have diff. formats
Most web browsers also support the idea of a "history" of URLs the user
has visited, and it displays them in a different style than normal URLs.
If the variable `url-keep-history' is `t', then Emacs/W3 keeps a
list of all the URLs visited in a session. The file is automatically
written to disk when exiting emacs. The list is added to those already
in the file specified by `url-global-history-file', which defaults to
`~/.mosaic-global-history'.
If any URL in the list is found in the file, it is not saved, but new
ones are added at the end of the file.
The function that saves the global history list is smart enough to
notice what style of history list is being used (Netscape, Emacs/W3, or
XMosaic), and writes out the new additions appropriately.
One of the nice things about keeping a global history files is that
Emacs/W3 can use it as a completion table. When doing `M-x w3-fetch',
pressing the `tab' or `space' key will show all completions for a
partial URL. This is very useful, especially for very long URLs that
are not in a hotlist, or for seeing all the pages from a particular web
site before choosing which to retrieve.
File: w3.info, Node: Stylesheets, Next: Supported URLs, Prev: Compatibility, Up: Top
Stylesheets
***********
The way in which Emacs/W3 formats a document is very customizable.
All formatting is now controlled by a default stylesheet set by the user
with the `w3-default-stylesheet' variable. Emacs/W3 currently supports
the W3C recommendation for Cascading Style Sheets, Level 1 (commonly
known as CSS1) with a few experimental items from other W3C proposals.
Wherever Emacs/W3 diverges from the specification, it will be clearly
documented, and will be changed once a full standard is available.
Support for DSSSL is progressing, but spare time is at an all-time
low. If anyone would like to help, please contact the author.
The following sections closely parallel the CSS1 specification so it
should be very easy to look up what Emacs/W3 supports when browsing
through the CSS1 specification. Please note that a lot of the text in
the following sections comes directly from the specification as well.
* Menu:
* Terminology:: Terms used in the rest of this chapter.
* Basic Concepts:: Why are stylesheets useful? Getting started.
* Pseudo-Classes/Elements:: Special classes for elements.
* The Cascade:: How stylesheets are combined.
* Properties:: What properties you can set on elements.
* Units:: What you can set them to.
File: w3.info, Node: Terminology, Next: Basic Concepts, Prev: Stylesheets, Up: Stylesheets
Terminology
===========
"attribute"
HTML attribute, ie: `align=center' - align is the attribute.
"author"
The author of an HTML document.
"block-level element"
An element which has a line break before and after (e.g. 'H1' in
HTML).
"canvas"
The part of the UA's drawing surface onto which documents are
rendered.
"child element"
A subelement in SGML terminology.
"contextual selector"
A selector that matches elements based on their position in the
document structure. A contextual selector consists of several
simple selectors. E.g., the contextual selector 'H1.initial B'
consists of two simple selectors, 'H1.initial' and 'B'.
"CSS"
Cascading Style Sheets.
"declaration"
A property (e.g. 'font-size') and a corresponding value (e.g.
'12pt').
"designer"
The designer of a style sheet.
"document"
HTML document.
"element"
HTML element.
"element type"
A generic identifier in SGML terminology.
"fictional tag sequence"
A tool for describing the behavior of pseudo-classes and
pseudo-elements.
"font size"
The size for which a font is designed. Typically, the size of a
font is approximately equal to the distance from the bottom of the
lowest letter with a descender to the top of the tallest letter
with an ascender and (optionally) with a diacritical mark.
"HTML extension"
Markup introduced by UA vendors, most often to support certain
visual effects. The FONT, CENTER and BLINK elements are examples
of HTML extensions, as is the BGCOLOR attribute. One of the goals
of CSS is to provide an alternative to HTML extensions.
"inline element"
An element which does not have a line break before and after (e.g.
'STRONG' in HTML)
"intrinsic dimensions"
The width and height as defined by the element itself, not imposed
by the surroundings. In this specification it is assumed that all
replaced elements - and only replaced elements - come with
intrinsic dimensions.
"parent element"
The containing element in SGML terminology.
"pseudo-element"
Pseudo-elements are used in CSS selectors to address typographical
items (e.g. the first line of an element) rather than structural
elements.
"pseudo-class"
Pseudo-classes are used in CSS selectors to allow information
external to the HTML source (e.g. the fact that an anchor has been
visited or not) to classify elements.
"property"
A stylistic parameter that can be influenced through CSS.
"reader"
The person for whom the document is rendered.
"replaced element"
An element that the CSS formatter only knows the intrinsic
dimensions of. In HTML, IMG, INPUT, TEXTAREA, SELECT and OBJECT
elements can be examples of replaced elements. E.g., the content
of the IMG element is often replaced by the image that the SRC
attribute points to. CSS1 does not define how the intrinsic
dimensions are found.
"rule"
A declaration (e.g. 'font-family: helvetica') and its selector
(e.g. 'H1').
"selector"
A string that identifies what elements the corresponding rule
applies to. A selector can either be a simple selector (e.g. 'H1')
or a contextual selector (e.g. 'H1 B') which consists of several
simple selectors.
"SGML"
Standard Generalized Markup Language, of which HTML is an
application.
"simple selector"
A selector that matches elements based on the element type and/or
attributes, and not the element's position in the document
structure. E.g., 'H1.initial' is a simple selector.
"style sheet"
A collection of rules.
"UA"
User Agent, often a web browser or web client.
"user"
Synonymous with reader.
"weight"
The priority of a rule.
File: w3.info, Node: Basic Concepts, Next: Pseudo-Classes/Elements, Prev: Terminology, Up: Stylesheets
Basic Concepts
==============
Designing simple style sheets is easy. One needs only to know a
little HTML and some basic desktop publishing terminology. E.g., to set
the text color of 'H1' elements to blue, one can say:
H1 { color: blue }
The example above is a simple CSS rule. A rule consists of two main
parts: selector ('H1') and declaration ('color: blue'). The declaration
has two parts: property ('color') and value ('blue'). While the example
above tries to influence only one of the properties needed for rendering
an HTML document, it qualifies as a style sheet on its own. Combined
with other style sheets (one fundamental feature of CSS is that style
sheets are combined) it will determine the final presentation of the
document.
The selector is the link between the HTML document and the style
sheet, and all HTML element types are possible selectors.
File: w3.info, Node: Pseudo-Classes/Elements, Next: The Cascade, Prev: Basic Concepts, Up: Stylesheets
Pseudo-Classes/Elements
=======================
In CSS1, style is normally attached to an element based on its
position in the document structure. This simple model is sufficient for
a wide variety of styles, but doesn't cover some common effects. The
concept of pseudo-classes and pseudo-elements extend addressing in CSS1
to allow external information to influence the formatting process.
Pseudo-classes and pseudo-elements can be used in CSS selectors, but
do not exist in the HTML source. Rather, they are "inserted" by the UA
under certain conditions to be used for addressing in style sheets.
They are referred to as "classes" and "elements" since this is a
convenient way of describing their behavior. More specifically, their
behavior is defined by a fictional tag sequence.
Pseudo-elements are used to address sub-parts of elements, while
pseudo-classes allow style sheets to differentiate between different
element types.
The only support pseudo-classes in Emacs/W3 are on the anchor tag
(<a>...</a>).
User agents commonly display newly visited anchors differently from
older ones. In CSS1, this is handled through pseudo-classes on the 'A'
element:
A:link { color: red } /* unvisited link */
A:visited { color: blue } /* visited links */
A:active { color: lime } /* active links */
All 'A' elements with an 'HREF' attribute will be put into one and
only one of these groups (i.e. target anchors are not affected). UAs may
choose to move an element from 'visited' to 'link' after a certain
time. An 'active' link is one that is currently being selected (e.g. by
a mouse button press) by the reader.
The formatting of an anchor pseudo-class is as if the class had been
inserted manually. A UA is not required to reformat a currently
displayed document due to anchor pseudo-class transitions. E.g., a style
sheet can legally specify that the 'font-size' of an 'active' link
should be larger that a 'visited' link, but the UA is not required to
dynamically reformat the document when the reader selects the 'visited'
link.
Pseudo-class selectors do not match normal classes, and vice versa.
The style rule in the example below will therefore not have any
influence:
A:link { color: red }
<A CLASS=link NAME=target5> ... </A>
In CSS1, anchor pseudo-classes have no effect on elements other than
'A'. Therefore, the element type can be omitted from the selector:
A:link { color: red }
:link { color: red }
The two selectors above will select the same elements in CSS1.
Pseudo-class names are case-insensitive.
Pseudo-classes can be used in contextual selectors:
A:link IMG { border: solid blue }
Also, pseudo-classes can be combined with normal classes:
A.external:visited { color: blue }
<A CLASS=external HREF="http://out.side/">external link</A>
If the link in the above example has been visited, it will be
rendered in blue. Note that normal class names precede pseudo-classes
in the selector.
File: w3.info, Node: The Cascade, Next: Properties, Prev: Pseudo-Classes/Elements, Up: Stylesheets
The Cascade
===========
In CSS, more than one style sheet can influence the presentation
simultaneously. There are two main reasons for this feature: modularity
and author/reader balance.
modularity
A style sheet designer can combine several (partial) style sheets
to reduce redundancy:
@import url(http://www.style.org/pastoral);
@import url(http://www.style.org/marine);
H1 { color: red } /* override imported sheets */
author/reader balance
Both readers and authors can influence the presentation through
style sheets. To do so, they use the same style sheet language
thus reflecting a fundamental feature of the web: everyone can
become a publisher. The UA is free to choose the mechanism for
referencing personal style sheets.
Sometimes conflicts will arise between the style sheets that
influence the presentation. Conflict resolution is based on each style
rule having a weight. By default, the weights of the reader's rules are
less than the weights of rules in the author's documents. I.e., if
there are conflicts between the style sheets of an incoming document
and the reader's personal sheets, the author's rules will be used. Both
reader and author rules override the UA's default values.
The imported style sheets also cascade with each other, in the order
they are imported, according to the cascading rules defined below. Any
rules specified in the style sheet itself override rules in imported
style sheets. That is, imported style sheets are lower in the cascading
order than rules in the style sheet itself. Imported style sheets can
themselves import and override other style sheets, recursively.
In CSS1, all '@import' statements must occur at the start of a style
sheet, before any declarations. This makes it easy to see that rules in
the style sheet itself override rules in the imported style sheets.
NOTE: The use of !important in CSS stylesheets is unsupported at
this time.
Conflicting rules are intrinsic to the CSS mechanism. To find the
value for an element/property combination, the following algorithm must
be followed:
1. Find all declarations that apply to the element/property in
question. Declarations apply if the selector matches the element in
question. If no declarations apply, the inherited value is used. If
there is no inherited value (this is the case for the 'HTML'
element and for properties that do not inherit), the initial value
is used.
2. Sort the declarations by explicit weight: declarations marked
'!important' carry more weight than unmarked (normal) declarations.
3. Sort by origin: the author's style sheets override the reader's
style sheet which override the UA's default values. An imported
style sheet has the same origin as the style sheet from which it
is imported.
4. Sort by specificity of selector: more specific selectors will
override more general ones. To find the specificity, count the
number of ID attributes in the selector (a), the number of CLASS
attributes in the selector (b), and the number of tag names in the
selector (c). Concatenating the three numbers (in a number system
with a large base) gives the specificity. Some examples:
LI {...} /* a=0 b=0 c=1 -> specificity = 1 */
UL LI {...} /* a=0 b=0 c=2 -> specificity = 2 */
UL OL LI {...} /* a=0 b=0 c=3 -> specificity = 3 */
LI.red {...} /* a=0 b=1 c=1 -> specificity = 11 */
UL OL LI.red {...} /* a=0 b=1 c=3 -> specificity = 13 */
#x34y {...} /* a=1 b=0 c=0 -> specificity = 100 */
Pseudo-elements and pseudo-classes are counted as normal elements
and classes, respectively.
5. Sort by order specified: if two rules have the same weight, the
latter specified wins. Rules in imported style sheets are
considered to be before any rules in the style sheet itself.
The search for the property value can be terminated whenever one rule
has a higher weight than the other rules that apply to the same
element/property combination.
This strategy gives author's style sheets considerably higher weight
than those of the reader. It is therefore important that the reader has
the ability to turn off the influence of a certain style sheet, e.g.
through a pull-down menu.
A declaration in the 'STYLE' attribute of an element has the same
weight as a declaration with an ID-based selector that is specified at
the end of the style sheet:
<STYLE TYPE="text/css">
#x97z { color: blue }
</STYLE>
<P ID=x97z STYLE="color: red">
In the above example, the color of the 'P' element would be red.
Although the specificity is the same for both declarations, the
declaration in the 'STYLE' attribute will override the one in the
'STYLE' element because of cascading rule number 5.
The UA may choose to honor other stylistic HTML attributes, for
example 'ALIGN'. If so, these attributes are translated to the
corresponding CSS rules with specificity equal to 1. The rules are
assumed to be at the start of the author style sheet and may be
overridden by subsequent style sheet rules. In a transition phase, this
policy will make it easier for stylistic attributes to coexist with
style sheets.
File: w3.info, Node: Properties, Next: Units, Prev: The Cascade, Up: Stylesheets
Properties
==========
In the text below, the allowed values for each property are listed
with a syntax like the following:
Value: N | NW | NE
Value: [ <length> | thick | thin ]{1,4}
Value: <uri>? <color> [ / <color> ]?
Value: <uri> || <color>
The words between < and > give a type of value. The most common types
are <length>, <percentage>, <url>, <number>and <color> these are
described in the section on [[units]]. The more specialized types (e.g.
<font-family>and <border-style>) are described under the property where
they appear.
Other words are keywords that must appear literally, without quotes.
The slash (/) and the comma (,) must also appear literally.
Several things juxtaposed mean that all of them must occur, in the
given order. A bar (|) separates alternatives: one of them must occur. A
double bar (A || B) means that either A or B or both must occur, in any
order. Brackets ([]) are for grouping. Juxtaposition is stronger than
the double bar, and the double bar is stronger than the bar. Thus "a b |
c || d e" is equivalent to "[ a b ] | [ c || [ d e ]]".
Every type, keyword, or bracketed group may be followed by one of the
following modifiers:
* An asterisk (*) indicates that the preceding type, word or group is
repeated zero or more times.
* A plus (+) indicates that the preceding type, word or group is
repeated one or more times.
* A question mark (?) indicates that the preceding type, word or
group is optional.
* A pair of numbers in curly braces ({A,B}) indicates that the
preceding type, word or group is repeated at least A and at most B
times.
Other than the value the following information is also shown.
Supported If this is present, it lists the parts of the
Values: specification that Emacs/W3 currently supports.
Unsupported If this is present, it represents the parts of the
Values: specifcation that Emacs/W3 does not support.
Initial: The default value for the property, unless explicitly set
in a stylesheet.
Applies to: What type of elements this property can be attached to.
Inherited: Yes or no
Percentage What a percentage value applies to when given.
values:
* Menu:
* Font Properties:: Selecting fonts, styles, and sizes.
* Colors and Backgrounds:: Controlling colors, front and back.
* Text Properties:: Alignment, decoration, and more!
* Box Properties:: Borders, padding, and margins, oh my!
* Classification:: Changing whitespace and display policies.
* Media Selection:: Conditionalize stylesheets on media-type.
* Speech Properties:: Speech output controlled by stylesheets.
File: w3.info, Node: Font Properties, Next: Colors and Backgrounds, Prev: Properties, Up: Properties
Font Properties
---------------
Setting font properties will be among the most common uses of style
sheets. Unfortunately, there exists no well-defined and universally
accepted taxonomy for classifying fonts, and terms that apply to one
font family may not be appropriate for others. E.g. 'italic' is commonly
used to label slanted text, but slanted text may also be labeled as
being Oblique, Slanted, Incline, Cursive or Kursiv. Therefore it is not
a simple problem to map typical font selection properties to a specific
font.
The properties defined by CSS1 are described in the following
sections.
* Menu:
* font-family:: Groups of fonts.
* font-style:: Normal, italic, or oblique?
* font-variant:: Small-caps, etc.
* font-weight:: How bold can you go?
* font-size:: How big is yours?
* font:: Shorthand for all of the above.
File: w3.info, Node: font-family, Next: font-style, Prev: Font Properties, Up: Font Properties
font-family
...........
Supported [[<family-name> | <generic-family>],]* [<family-name> |
Values: <generic-family>]
Initial: User specific
Applies to: all elements
Inherited: yes
Percentage N/A
values:
The value is a prioritized list of font family names and/or generic
family names. Unlike most other CSS1 properties, values are separated
by a comma to indicate that they are alternatives:
BODY { font-family: gill, helvetica, sans-serif }
There are two types of list values:
<family-name>
The name of a font family of choice. In the last example, "gill"
and "helvetica" are font families.
<generic-family>
In the example above, the last value is a generic family name. The
following generic families are defined:
* 'serif' (e.g. Times)
* 'sans-serif' (e.g. Helvetica)
* 'cursive' (e.g. Zapf-Chancery)
* 'fantasy' (e.g. Western)
* 'monospace' (e.g. Courier)
Style sheet designers are encouraged to offer a generic font family
as a last alternative.
Font names containing whitespace should be quoted:
BODY { font-family: "new century schoolbook", serif }
<BODY STYLE="font-family: 'My own font', fantasy">
If quoting is omitted, any whitespace characters before and after the
font name are ignored and any sequence of whitespace characters inside
the font name is converted to a single space.
File: w3.info, Node: font-style, Next: font-variant, Prev: font-family, Up: Font Properties
font-style
..........
Supported normal | italic | oblique
Values:
Initial: normal
Applies to: all elements
Inherited: yes
Percentage N/A
values:
The 'font-style' property selects between normal (sometimes referred
to as "roman" or "upright"), italic and oblique faces within a font
family.
A value of 'normal' selects a font that is classified as 'normal' in
the UA's font database, while 'oblique' selects a font that is labeled
'oblique'. A value of 'italic' selects a font that is labeled 'italic',
or, if that is not available, one labeled 'oblique'.
The font that is labeled 'oblique' in the UA's font database may
actually have been generated by electronically slanting a normal font.
Fonts with Oblique, Slanted or Incline in their names will typically
be labeled 'oblique' in the UA's font database. Fonts with Italic,
Cursive or Kursiv in their names will typically be labeled 'italic'.
H1, H2, H3 { font-style: italic }
H1 EM { font-style: normal }
In the example above, emphasized text within 'H1' will appear in a
normal face.