REL=Home
Link points to home or top page in hierarchy.
REL=ToC
Link points to a table of contents.
REL=Index
Link points to an index for the current page.
REL=Glossary
Link points to a glossary.
REL=Copyright
Link points to a page with copyright information for the current page.
REL=Up
Link points to the pages parent in the hierarchy.
REL=Next
Link points to the next page in a series of pages.
REL=Previous
Link points to the previous page in a series of pages.
REL=Help
Link points to information that may further explain the page to the user.
REL=Bookmark
Link points to a particular location within a long document. The TITLE attribute is used to label the bookmark.

What good is it?

Okay, so what good is it? Well, if a webmaster adds the REL tags to the HTML page you are viewing, you can use these links if your browser includes a 'Site navigation bar'.

 

HTML Examples:

<link rel="previous" href="[previous url here]"/>
<link rel="next" href="[next url here]"/>
<link rel="first" href="[first url here]"/>
<link rel="last" href="[last url here]"/>

Opera browser's Site Navigation Bar:

Here are the ones in Opera7's bar, in the order in which they appear:

start, index, contents, search, glossary, help, first, prev, next, last, up, copyright, and author.

(Note: start is displayed as "Home" in the bar.)

Mozilla Site Navigation Bar:

The following is copied from http://nwalsh.com/hacks/mozilla/

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Mozilla Site Navigation

This hack is no longer required as of Mozilla 1.1!

Early release candidates of Mozilla included a very cool feature: a site navigation tool bar. With this feature enabled, the browser adds a toolbar with buttons that provide access to the LINK elements in the HTML HEAD.

Recent versions of the Website doctype include these links, so you can navigate through the website using the Mozilla UI:
A Mozilla Screen Snapshot

Unfortunately, the Mozilla folks decided to remove this feature shortly before the 1.0 release. Apparently it had a small but measurable performance impact.

Personally, I could care less about the performance impact; the feature is way too valuable to worry about losing a few percentage points in page loading speed.

Patching Mozilla to Enable Site Navigation

These instructions work for me, on my Linux box. I assume something similar will work on a Windows box or a Mac, but I haven't tried it. You have backups, right? Caveat hacker.

I've installed Mozilla in /usr/local/mozilla; adjust the paths below to reflect the location where you installed it.

1.

Unpack the /usr/local/mozilla/chrome/comm.jar file into some temporary location:

$ cd /tmp
$ mkdir moz
$ cd moz
$ jar xf /usr/local/mozilla/chrome/comm.jar

If you don't have the jar command on your system, get it from one of the Sun Java distributions.

[[ WINDOWS USERS: [comm.jar] is just a compressed file. Use 7-Zip to extract/explore the 'archive'. ]]


2.

Unpacking the comm.jar file will produce a tree of several hundred files. Edit ./content/navigator/navigator.xul. This is an XML document.

$ emacs -nw /tmp/moz/content/navigator/navigator.xul

About 25 lines down from the top of this file, you'll find a bunch of “xul-overlay” processing instructions. Add the following processing instruction to the end of that group:

<?xul-overlay href="chrome://navigator/content/linkToolbarOverlay.xul"?>

Save navigator.xul.

At this point, you've made all the changes that are needed to enable the site navigation toolbar. However, the toolbar is itself defined with XUL, Mozilla's XML User Interface language. I decided to “improve” the site navigation toolbar to work better with DocBook documents. If you want to install my patched toolbar, continue with step 3. If you just want the standard toolbar, skip to step 4.
3.

Download linkToolbarOverlay.xul and copy it into the navigator directory:

$ wget http://nwalsh.com/hacks/mozilla/linkToolbarOverlay.xul
mv linkToolbarOverlay.xul /tmp/moz/content/navigator/

4.

Now all we have to do is install our patched files. First, build a new comm.jar file:

$ cd /tmp/moz
$ jar cf comm.jar content

5.

Next, make a copy of the original jar file and replace it with your new one. Depending on where and how you installed Mozilla, you may need root or administrator privileges to do this.

$ cd /usr/local/mozilla/chrome
$ mv comm.jar comm.jar.ORIG
$ mv /tmp/moz/comm.jar .

6.

Exit and restart Mozilla.
7.

On the View -> Show/Hide menu, you should find a new entry for the Site Navigation Bar. You can enable it always or as needed. Either way, when you visit sites or documents that are using navigation links, you'll get the new toolbar.

This hack was inspired by a thread I found in the Mozilla newsgroups.

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