Summary of Tags Related to Linking
Simple Hypertext Links
Linking Within a Document
Affecting the Appearance of Links
Non-Web Links and Protocols
Linking Documents with <link>
The HTML 4.01 specification puts it simply and clearly: "A link is a connection from one web resource to another." This ability to link one document to another is what makes HTML unique among document markup languages and is the key to its widespread popularity.
This chapter focuses on the HTML tags related to linking and building relationships between documents. It includes uses for the anchor tag, linking with imagemaps (both client- and server-side), affecting the appearance of hyperlinks, creating links with non-web protocols, and associating documents with the link tag.
In this section, browser support for each tag is noted to the right of the tag name. Browsers that do not support the tag are grayed out. Tag usage is indicated below the tag name. Start and end tags are required unless otherwise noted. "Deprecated" means that the tag or attribute is currently supported but is due to be phased out of the HTML specification and is discouraged from use (usually in favor of similar style sheet controls). The attributes listed for each tag reflect those in common use. A more thorough listing of attributes for each tag, according to the HTML 4.01 specification, appears in Appendix A, "HTML Elements".
|<a>||NN 2, 3, 4, 6 MSIE 2, 3, 4, 5, 5.5, 6 HTML 4.01 WebTV Opera5|
Defines an anchor within the document. An anchor is used to link to another document or web resource. It can also serve to label a fragment within a document (also called a named anchor), which serves as a destination anchor for linking to a specific point in an HTML document.
The attributes labeled "HTML 4.01" are new to the HTML 4.01 specification and are generally supported only by Internet Explorer 5.5 and higher and Netscape 6.
HTML 4.01. Assigns an access key (shortcut key command) to the link. Access keys are also used for form fields. The value is a single character. Users may access the element by hitting Alt-key (PC) or Ctrl-key (Mac).
HTML 4.01. Specifies the character encoding of the target document. See Chapter 7, "Internationalization" for information on character sets.
HTML 4.01. Specifies the x,y coordinates for a clickable area in an imagemap. HTML 4.0 proposes that client-side imagemaps be replaced by an <object> tag containing the image and a set of anchor tags defining the "hot" areas (with shapes and coordinate attributes). This system has not yet been implemented by browsers.
Specifies the URL of the destination HTML document or web resource (such as an image, audio, PDF, or other media file).
Gives the link a unique name (similar to the name attribute) so it can be referenced from a link, script, or style sheet. It is more versatile than name, but it is not as universally supported.
HTML 4.01. Specifies the base language of the target document. See Chapter 7, "Internationalization" for a list of two-letter language codes.
Places a fragment identifier within an HTML document. Fragments are discussed further in Section 11.3, "Linking Within a Document" in this chapter.
Establishes a relationship between the current document and the target document. Common relationships include stylesheet, next, prev, copyright, index, and glossary.
Specifies the relationship from the target back to the source (the opposite of the rev attribute).
HTML 4.01. Defines the shape of a clickable area in an imagemap. This is only used in the <a> tag as part of HTML 4.01's proposal to replace client-side imagemaps with a combination of <object> and <a> tags. This system has not yet been implemented by browsers.
HTML 4.01. Specifies the position of the current element in the tabbing order for the current document. The value must be between 0 and 32767. It is used for tabbing through the links on a page (or fields in a form).
Not supported by WebTV or Internet Explorer 2.0 and earlier. Specifies the name of the window or frame in which the target document should be displayed. For more information, see Section 11.5, "Targeting Windows" in this chapter and Section 14.5, "Targeting Frames" in Chapter 14, "Frames".
To a local file:
To an external file:
To a named anchor:
To a named anchor in the current file:
To send an email message:
<A HREF="mailto:[email protected]">...</A>
To a file on an FTP server:
<A HREF="ftp://server/path/filename">... </A>
|<area>||NN 2, 3, 4, 6 MSIE 3, 4, 5, 5.5, 6 HTML 4.01 WebTV Opera5|
<area> (no end tag)
The area tag is used within the <map> tag of a client-side imagemap to define a specific "hot" (clickable) area. Client-side imagemaps are discussed later in this chapter.
Required. Specifies a short description of the image that is displayed when the image file is not available.
Specifies a list of comma-separated pixel coordinates that define a "hot" area of an imagemap. The specific syntax for the coordinates varies by shape (see Section 11.6, "Imagemaps" later in this chapter).
Specifies the URL of the document or file that is accessed by clicking on the defined area.
Defines a "mouse-sensitive" area in an imagemap for which there is no action when the user clicks in the area.
Defines the shape of the clickable area.
|<base>||NN 2, 3, 4, 6 MSIE 2, 3, 4, 5, 5.5, 6 HTML 4.01 WebTV Opera5|
<base> (no end tag)
Specifies the base pathname for all relative URLs in the document. Place this element within the <head> of the document.
|<link>||NN 4, 6 MSIE 2, 3, 4, 5, 5.5, 6 HTML 4.01 WebTV Opera5|
<link> (no end tag)
Defines a relationship between the current document and another document. This tag goes within the <head> portion of the document. It is often used to refer to an external style sheet.
Identifies the target medium for the linked document so an alternate style sheet can be accessed. The media attribute is explained in more detail in Chapter 5, "Printing from the Web".
Describes the relationship from the current source document to the target. Common relationship types include stylesheet, next, prev, copyright, index, and glossary.
Specifies the relationship of the target document back to the source (the opposite of the rel attribute).
|<map>||NN 2, 3, 4, 6 MSIE 2, 3, 4, 5, 5.5, 6 HTML 4.01 WebTV Opera5|
Encloses client-side imagemap specifications. Client-side imagemaps are discussed later in this chapter.
Copyright © 2002 O'Reilly & Associates. All rights reserved.