3       Web Navigation



Several options are built in to NCSA Mosaic to help you move 
among documents. These include hyperlinks, the Forward and 
Backward buttons, as well as History and Hotlist on the Navigate 
menu.

Moving Around

Think of the documents you have viewed using NCSA Mosaic 
as being a stack of papers on your desk. Instead of looking 
through the papers, you are viewing them in an NCSA Mosaic 
window. Document1 is at the bottom, with document5 on top 
of that, then document7, and document14 on the very top. 
You are viewing document14.

Figure 3.1       A Stack of Documents

You have two ways to move forward (the hyperlink and the 
Forward button) and two ways to move back to one of the ear-
lier documents (the Back button and Window History).

Using Hyperlinks

An underlying philosophy of the Web is that documents pro-
vide you with hyperlinks to other related information. These 
hyperlinks provide the web elements that give the Web its 
name. You can follow the same hyperlink an infinite number 
of times.

A hyperlink (sometimes called an anchor) is a highlighted 
word or graphic that, when activated (clicked on), takes you 
to a new document or resource somewhere on the Internet. 
The new document can be, among other things, a text file, a 
graphic, an audio clip, a telnet session, or a WAIS (an indexing 
and retrieval system) search. Hyperlinks are established by 
the author of a document.

Hyperlinks to other documents are designated by highlighted 
words or outlined graphics. NCSA Mosaic highlights one of 
the following ways:

       color 

       underlining 

       both color and underlining 

NOTE: The color and underlining defaults can be changed in 
your .Xdefaults file. See System Configuration and Modifi-
cation Assistance on pageC1 for additional information. 
Underlining can also be changed using Anchor Underlines on 
the Options menu. 

To activate a hyperlink, single click with the left mouse but-
ton on the word or graphic that is highlighted. 

Once you view a hyperlinked document, the hyperlink in the 
original file changes its appearance. For example, if an 
unviewed hyperlink is underlined, the underlining becomes 
broken (or dashed) after viewing. If the hyperlink is displayed 
in a color, the color changes after viewing. You can view 
hyperlinked documents again.

All other references to the same document change to show 
that you have already viewed it. For example, if you are read-
ing document1, and you activate a hyperlink to document5, 
the next hyperlink to document5 (which could be in 
document14) is shown as viewed (with a different color or a 
change in the underlining style).

The Forward Button

One way to move forward is to single click with your left 
mouse button on a hyperlink included in a document. 
Remember you can follow the same hyperlink an infinite 
number of times.

Generally you move to another document by following a 
hyperlink. If you have retraced your steps to a previous docu-
ment (see below), you can move to the most recent document 
by clicking on the Forward button in the bottom control panel 
of the Document View window.

For example, using the same stack described above, if you 
view document14 and moved backward to document7 using 
one of the methods described in the next two sections, you 
can move forward to document14 by clicking on the Forward 
button.

The Forward button is dimmed (right, below) if NCSA Mosaic 
has no document to move forward to.

Figure 3.2       Forward Button 

If one of the documents you look at was opened by an exter-
nal viewer (such as xv), you cannot return to it without click-
ing on the hyperlink again. NCSA Mosaic does not include 
documents viewed with the external programs in its tracking 
of where you have been.

The Back Button

The Back button in the bottom control panel returns you to 
the last document you viewed. In the sample stack shown 
above, pressing the Back button returns you to document7. 
Pressing it again returns you to document5.

Going Back to an Internal Hyperlink

Some documents have a set of internal hyperlinks from one 
location in a document to another location in the same docu-
ment. Those hyperlinks tell NCSA Mosaic to move from one 
location in the document to another in the same document. 
In this case, using the Back menu option or button returns 
you to the start of the hyperlink.

An example of internal hyperlinks can be found in the Begin-
ners Guide to HTML on the NCSA Mosaic Help menu. The 
table of contents on the first screen of that document is a 
set of internal hyperlinks within that guide. The Back button 
returns you to the start of the hyperlink.

Window History

NCSA Mosaic keeps track of most documents you view dur-
ing your session. (It does not record the documents seen with 
external viewers such as xv.) The list of documents you have 
viewed is maintained in the Window History window.

Figure 3.3       Window History Window 

Selecting Window History from the Navigate menu brings up the 
Window History window showing Where youve been. This lists 
the documents you have viewed in sequential order. In the 
list shown above, you can easily return to the NCSA Home 
Page by opening your Window History and doubleclicking on 
the NCSA Home Page from the list of viewed documents. (You 
can also use the middle mouse button to select the docu-
ment.) Using Window History is often the quickest way to return 
to a document you viewed many hyperlinks ago.

Exploring on Your Own

One of the best features of NCSA Mosaic is how easily you 
can move through the global web of information available 
online. Each hyperlink moves you to yet another document 
available on the Web. 

The Navigate and Help menus give you three good places to 
start your explorations. The documents listed below are 
retrieved from the NCSA Web server:

       On the Navigate menu: Internet Starting Points lists interest-
ing documents on the Internet including some home 
pages, services, hyperlinks to other types of servers, and 
information sources of particular interest to new users.

       On the Navigate menu: Internet Resources Meta-Index compiles 
the various resource directories and indices available on 
the Web. 

       On the Help menu: Mosaic Whats New Page is the best way to 
find out about new resources, interesting additions to 
existing resources, as well as fun exhibits on the Internet. 
This document is updated frequently, so check it often.

To learn more about NCSA Mosaics capabilities, check the 
Demo... document available from the Help menu. It walks you 
through what NCSA Mosaic can do and hyperlinks to some 
outstanding examples of hypermedia on the Internet.

Global History

NCSA Mosaic not only keeps track of documents you have 
viewed in the current session but also the documents you 
have viewed in all your NCSA Mosaic sessions to date. This 
information is stored in the .mosaic-global-history file (the 
default name) in your home directory. By maintaining the his-
tory list, NCSA Mosaic knows which hyperlinks to show as 
displayed (in the viewed color or with broken underlining
also known as visited and unvisited hyperlinks). 

Your global history file, obviously, grows with each NCSA 
Mosaic session. You may want to clear the history file period-
ically to save disk space or to refresh all the hyperlinks. 
Selecting Clear Global History... from the Navigate menu and con-
firming your choice clears the .mosaic-global-history file. All 
hyperlinks change from viewed to unviewed.

Opening Documents Directly

On occasion you may want to open a document directly 
instead of connecting to a document through a series of 
hyperlinks. To do this, use the Uniform Resource Locator, or 
URL for short. URLs combine the protocol, name of the 
machine serving the file to the Internet, and the path and file-
name. 

To open a document directly, select Open from the File menu 
and enter the URL in the URL To Open field that appears in the 
dialog box. Your cursor must be in the field in the dialog box 
to type. 

The URL Format

A URL consists of a reference to the type of server being 
accessed and, essentially, the path for the specific document. 
Sometimes the port number of the server is also included, 
and sometimes a filename is not included because a default 
file to open has been set in a directory. When you click on a 
hyperlink, NCSA Mosaic interprets the URL and retrieves the 
document by connecting to the Internet server that is speci-
fied in the URL. The file is then shown to you.

The required URL format is:

scheme://host.domain[:port]/path/filename

where scheme is one of the following:

        Name    Server Type

        file    your local system or an anonymous FTP (File 
Transfer Protocol) server

        FTP     an anonymous FTP server

        HTTP    a World Wide Web server (HTTP stands for 
hypertext transferprotocol)

        gopher  a Gopher server

        news    an NNTP news server

        telnet  opens a telnet session

        WAIS    a WAIS (Wide Area Information Server) 
server

For example, the URL for the NCSA home page is:

http://www.ncsa.uiuc.edu/General/NCSAHome.html

where:

        http is the type of server being run (a Web server)

        www.ncsa.uiuc.edu is the Internet address of the NCSA Web 
server

        /General is the directory containing the Home Page

        NCSAHome.html is the file served to you

For more information about URLs, refer to A Beginners Guide 
to URLs on the NCSA Mosaic Help menu or to the original URL 
information file from CERN (available as a hyperlink at the 
end of the Beginners Guide).

Displaying the URL

The cursor becomes a small hand when you have it over a 
hyperlink. The URL of the document under the hand pointer 
is shown in the information line on the Document View win-
dow. This tells you where NCSA Mosaic will go to retrieve this 
document.

Another way to see the URL for a document is to open the 
document source file by choosing View Source... from the File 
menu. The Document Source window displays the coded file 
that is being interpreted by NCSA Mosaic (see HyperText 
Markup Language on page51 for more information on the 
coded file). 

Using Hotlists

What is a Hotlist?

The hotlist function lets you build a list of documents on the 
Web that you find useful or interesting and to which you 
want to be able to move quickly. You can add or delete docu-
ments easily. Add documents to which you expect to refer 
frequently, documents that refer to a specific topic, or docu-
ments that you want to tell others about. 

To look at the organization of the hotlist, open the Hotlist 
View window by selecting Hotlist from the Navigate menu. If 
you have not added any documents to your hotlist yet, it is 
empty. If you have added a document, the document title 
appears in the scroll box, as shown in Figure 3.4.

Figure 3.4       Hotlist View Window

Adding Documents

To add a document to your hotlist:

1.      Go to the document you want to add. 

2.      Select Add Current to Hotlist from the Navigate menu.

This appends the documents URL to the hotlist and displays 
the document title in the Hotlist window.

The other way to add a document is to:

1.      Go to the document you want to add.

2.      Select Hotlist from the Navigate menu.

3.      Click Add Current.

Removing Documents

To remove a document from your hotlist:

1.      Choose Hotlist from the Navigate menu.

2.      Select the entry to be deleted.

3.      Click Remove. 

Editing Hotlist Information

Edit the title of any entry in the hotlist by selecting the entry 
and clicking on Edit Title. The Edit Hotlist Entry Title opens. 
Enter additional information or modify the default informa-
tion as you like. Click Commit to save the changes.

For example, you might want to add the authors name or ini-
tials or the location of the server providing the document.

Linking to Other Documents

Move to any document in the hotlist by double-clicking on 
the entry, or by selecting the entry and clicking on the Go To 
button. 

Sharing Your Hotlist

Use the Mail To... button at the bottom of the Hotlist View win-
dow to send your hotlist via electronic mail to a colleague. 
The electronic mail is an HTML document (see HyperText 
Markup Language on page51 for more information on the 
mark-up language used to prepare Web documents). 

Mailing your hotlist to a colleague is a way to share your 
favorite or frequently used URLs. The recipient can use NCSA 
Mosaic for X Window System to open the hotlist as a WWW 
document by copying the electronic mail to a file, saving it 
with the .html extension, and opening it as a local document 
within NCSA Mosaic. Use Open Local... on the File menu. The 
hotlist hyperlinks can then be used by the recipient. 

Figure 3.5 shows a sample hotlist. The tags shown between 
angle brackets (e.g., <H1>, </H1>, <DL>, etc.) are all HTML 
codes. Document URLs follow the <A HREF= tags.

Figure 3.5       Sample Hotlist as Mailed

<HTML>

<H1>Hotlist From E. Ogilvie, 277 English Building</H1>

<DL>

<DT>NCSA Home Page

<DD><A HREF="http://www.ncsa.uiuc.edu/General/NCSAHome.html">http://
www.ncsa.uiuc.edu/General/NCSAHome.html
</A>

<DT>Cornell Theory Center Home Page

<DD><A HREF="http://www.tc.cornell.edu:80/ctc.html">http://
www.tc.cornell.edu:80/ctc.html</A>

<DT>Bill's Lighthouse Getaway

<DD><A HREF="http://gopher.lib.utk.edu:70/0/Other-Internet-Resources/
pictures/lights/lights.html">http://gopher.lib.utk.edu:70/0/Other-
Internet-Resources/pictures/lights/lights.html</A>

</DL>

</HTML>

Searching Documents

The Find In Current... option in the File menu opens a Find in 
Document window from which you can search for strings of 
characters inside the current document.

Figure 3.6       Find in Document Window

Searching starts from the top of the document. Type in the 
search term, and click the Find button. NCSA Mosaic moves to 
the first occurrence of the search term and highlights the 
matched text. Clicking Find again moves to the next occur-
rence of the search term. A dialog box tells you when there 
are no more matches. (Pressing the RETURN key on your key-
board with the cursor in the text field is equivalent to clicking 
Find.)

Use the Reset button to clear your current search text and 
reset the search position.

Every time you view a new document, the search position is 
reset to the top of the document as if Reset had been 
pushedbut the search text itself is not cleared.

Click on Dismiss to terminate your search and close the win-
dow.

The two toggle buttons in the search window are for:

        Caseless Search If this is on, matches are made regardless of 
case. If it is toggled off, case is significant.

        Backwards Search        If this is on, the next search action looks for 
a preceding occurrence of the text (from the 
cursors current position to the top of the 
file).
