You can preview documents in progress with NCSA Mosaic (and some other WWW browers). Open the document using the Open Local option under the File menu. Use the Filters, Directories, and Files fields to locate the document or enter the path and name of the document in the Name of Local Document to Open field. Press OK. If you see edits you want to make, enter them in the source file. Save the changes. Return to NCSA Mosaic and press the Reload button on the bottom menu. The edits are reflected in the on-screen display.
<TITLE>The simplest HTML example</TITLE> <H1>This is a level one heading</H1> Welcome to the world of HTML. This is one paragraph.<P> And this is a second.<P>____________________________________________________________________ Click here to see the formatted version of the example.
HTML uses tags to tell the World Web viewer how to display the text. The above example uses
<TITLE>tag (which has a correspondinging
</TITLE>tag), which specifies the title of the document,
<H1>header tag (with corresponding
<), known as a ``less than'' symbol to mathematicians, followed by some text (called the directive ) and closed by a right angular bracket (
>). Tags are usually paired, e.g.
</H1>. The ending tag looks just like the starting tag except a slash (/) precedes the text within the brackets. In the example,
<H1>tells the viewer to start formatting a top level heading;
</H1>tells the viewer that the heading is complete.
The primary exception to the pairing rule is the
end-of-paragraph tag. There is no such thing as
is completely equivalent to
Not all tags are supported by all World Wide Web browsers. If a browser does not support a tag, it should just ignore it, though.
Every HTML document should have a title. A title is generally displayed separately from the document and is used primarily for document identification in other contexts (e.g., a WAIS search). Choose about half a dozen words that describe the document's purpose.
In NCSA Mosaic, the Document Title field is at the top of the screen just below the pulldown menus.The directive for the title tag is
<title>. The title generally goes on the first line of the document.
HTML has six levels of headings (numbered 1 through 6), with 1 being the most prominent. Headings are displayed in larger and/or bolder fonts than the normal body text. The first heading in each document should be tagged
. The syntax of the heading tag is:
<Hy >Text of heading </Hy >where y is a number between 1 and 6 specifying the level of the heading.
For example, the coding for the ``Headings'' section heading above is
<H3>Headings</H3>Title versus first heading : In many documents (including this one), the first heading is identical to the title. For multi-part documents, the text of the first heading should be suitable for a reader who is already browsing related information (e.g., a chapter title), while the title tag should identify the node in a wider context (e.g., include both the book title and the chapter title).
Unlike documents in most word processors, carriage returns and white space in HTML files aren't significant. Word wrapping can occur at any point in your source file, and multiple spaces are collapsed into a single space (except in the <TITLE> field). Notice that in the barebones example, the first paragraph is coded as
Welcome to HTML. This is the first paragraph. <P>In the source file, there is a line break between the sentences. A Web browser ignores this line break and starts a new paragraph only when it reaches a
You must end each paragraph with
. The viewer ignores any indentations or blank lines in the source text. Without the
tags, the document becomes one large paragraph. HTML relies almost entirely on the tags for formatting instructions. (The exception is text tagged as ``preformatted,'' explained
.) For instance, the following would produce identical output as the first barebones HTML example:
<TITLE>The simplest HTML example</TITLE><H1>This is a level one heading</H1>Welcome to the world of HTML. This is one paragraph.<P>And this is a second.<P>________________________________________________________________________ However, to preserve readability in HTML files, headings should be on separate lines, and paragraphs should be separated by blank lines.
In NCSA Mosaic, hypertext links are in color and underlined by default. It is possible to modify this in the Options menu as well as in your .Xdefaults file.HTML's single hypertext-related directive is
A, which stands for anchor. To include anchors in your document:
href="filename.html"followed by a closing angle bracket:
<a href="MaineStats.html">Maine</a>This entry makes ``Maine'' the hyperlink to the document MaineStats.html .
Uniform Resource Locator
A Uniform Resource Locator (URL) refers to the format used by WWW documents to locate other files. A URL gives the type of resource being accessed (e.g., gopher, WAIS) and the path of the file. The format used is:
scheme ://host.domain [:port ]/path /filenamewhere scheme is one of:
telnet, but these are used much less often than the above. The port number can generally be omitted from the URL.
For example if you wanted to insert a link to this primer, you would insert
<A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html"> NCSA's HTML Primer</A>into your document. This would make the text ``NCSA's HTML Primer'' a hyperlink leading to this document. Refer to the Addressing document prepared by CERN for additional information about URLs. A Beginner's Guide to URLs is located on the NCSA Mosaic Help menu.
Anchors to Specific Sections in Other Documents
Anchors can also be used to move to a particular section in a document. Suppose you wish to set a link from document A and a specific section in document B. First you need to set up what is called a
in document B. For example, to add an anchor named ``Jabberwocky" to document B, you would insert
Here's <A NAME="Jabberwocky">some text</a>.Now when you create the link in document A, you include not only the filename, but also the named anchor, separated by a hash mark(``#''):
This is my <A HREF="documentB.html#Jabberwocky">link</a>.Now clicking on the word ``link'' in document A would send the reader directly to the words ``some text'' in document B.
Note: The NCSA Mosaic Back button does not work for an anchor within a document because the Back button is designed to move to a previous document. Move back manually within the document using the scroll bar. (The Back button will return to the start of a hyperlink effective with Version 2.0 of NCSA Mosaic.)
Additional markup tags
The above is sufficient to produce simple HTML documents. For more complex documents, HTML also has tags for several types of lists, extended quotes, character formatting and other items, all described below.
HTML supports unnumbered, numbered, and descriptive lists. For list items, no paragraph separator is required. The tags for the items in the list terminate each list item.
<li>tag followed by the individual item. (Remember that no closing tag is needed.)
<UL> <LI> apples <LI> bananas </UL>The output is:
Note that different viewers display an unordered list differently. A viewer might use bullets, filled circles, or dashes to show the items.
A numbered list (also called an ordered list, from where the abbreviation comes) uses the
directive to start a list rather than the
directive. The items are tagged using the same
tag as for a bulleted list. For example:
<OL> <LI> oranges <LI> peaches <LI> grapes </OL>The list looks like this online:
A description list usually consists of alternating a
(abbreviated as dt) and a
(abbreviated as dd). The description generally starts on a new line, because the viewer allows the full line width for the contents of the dt field.
Below is an example description list as included in your source file:
<DL> <DT> National Center for Supercomputing Applications <DD> NCSA is located on the campus of the University of Illinois at Urbana-Champaign. NCSA is a one of four member institutions in the National Metacenter for Computational Science and Engineering. <DT> Cornell Theory Center <DD> CTC is located on the campus of Cornell University in Ithaca, New York. CTC is another member of the National Metacenter for Computational Science and Engineering. </DL>The output looks like this:
<DD>entries can contain multiple paragraphs (separated by paragraph tags), lists, or other description information.
Lists can be arbitrarily nested. A list item can itself contain lists. You can also have a number of paragraphs, each themselves containing nested lists, in a single list item, and so on.
Remember that the display of an unordered list varies with the viewer. A browser may not provide successive levels of indentation or modify the bullets used at each level.
NCSA Mosaic indents the second level in the following list and changes the ``bullet'' from a bullet to a small box.An example nested list:
<UL> <LI> A few New England states: <UL> <LI> Vermont <LI> New Hampshire </UL> <li> One Midwestern state: <UL> <LI> Michigan </UL> </UL>The nested list is displayed as
pretag (which stands for ``preformatted'') to include text in a fixed-width font and to cause spaces, new lines, and tabs to be significant. This is useful for program listings. For example, the following lines in your source file:
<PRE> #!/bin/csh cd $SCR cfs get mysrc.f:mycfsdir/mysrc.f cfs get myinfile:mycfsdir/myinfile fc -02 -o mya.out mysrc.f mya.out cfs save myoutfile:mycfsdir/myoutfile rm * </PRE>display as:
#!/bin/csh cd $SCR cfs get mysrc.f:mycfsdir/mysrc.f cfs get myinfile:mycfsdir/myinfile fc -02 -o mya.out mysrc.f mya.out cfs save myoutfile:mycfsdir/myoutfile rm *Hypertext references (and other HTML tags) can be used within <pre> sections.
</blockquote>tags to include quotations in a separate block on the screen.
<blockquote> Let us not wallow in the valley of despair. I say to you, my friends, we have the difficulties of today and tomorrow. <P> I still have a dream. It is a dream deeply rooted in the American dream. <P> I have a dream that one day this nation will rise up and live out the true meaning of its creed. We hold these truths to be self-evident that all men are created equal. <P> </blockquote>The result is
Let us not wallow in the valley of despair. I say to you, my friends, we have the difficulties of today and tomorrow.
I still have a dream. It is a dream deeply rooted in the American dream.
I have a dream that one day this nation will rise up and live out the true meaning of its creed. We hold these truths to be self-evident that all men are created equal.
<ADDRESS>tag is generally used within HTML documents to specify the author of a document and provides a means of contacting the author (e.g., an email address). This is usually the last item in a file and generally starts on a new, left-justified line.
For example, the last part of the HTML file for this primer is
<ADDRESS> A Beginner's Guide to HTML / NCSA / firstname.lastname@example.org </ADDRESS>The result is: A Beginner's Guide to HTML / NCSA / email@example.com
Individual words or sentences can be put in special styles.
styles are those that are configured by your viewer. For example,
may be defined as italic by your viewer. Each time you enter
tags, the viewer automatically displays the text in italics.
style is one that you determine, and the viewer displays what you have coded. For example
tells the viewer to display your text in italics.
For HTML-coded documents, you should use logical styles whenever possible. Future implementations of HTML may not implement physical styles at all.
<I>text</i>puts text in italics (HTML Primer )
<em>text</em>also italicizes text (only one viewer)
<cite>text</cite>is used for citations of names of manuals, sections, or books (HTML Primer )
<var>text</var>indicates a variable (filename )
<b>text</b>puts text in bold (Important)
<strong>text</strong>also emphasizes text (Note:)
<tt>text</tt>puts text in a fixed-width font (1 SU = 1 CPU hour)
<code>text</code>also puts text in a fixed-width font (
1 SU = 1 CPU hour)
<samp>text</samp>formats text for samples (-la)
<kbd>text</kbd>displays the names of keys on the keyboard (HELP)
<dfn>text</dfn>displays a definition in italics
<), right angle bracket (
>), and ampersand (
The angle brackets are used to specify HTML tags (as shown above), while the ampersand is used as the escape mechanism for these and other characters:
<is the escape sequence for
>is the escape sequence for
&is the escape sequence for
There are additional escape sequences, such as a whole set of sequences to support 8-bit character sets (ISO 8859-1). For example:
öis the escape sequence for a lowercase
owith an umlaut: ö
ñis the escape sequence for a lowercase
nwith an tilde: ñ
Èis the escape sequence for an uppercase
Ewith a grave mark: È
NCSA Mosaic is can display X Bitmap (XBM) or GIF format images inside documents.
Each image takes time to process and slows down the initial display of the document
. Using a particular image multiple times in a document causes very little performance degradation compared to using the image only once.
tag is an HTML extension first implemented in NCSA Mosaic. Currently it is not understood by most other World Wide Web browsers.
To include an inline image in your document, enter:
<IMG SRC="filename.GIF">By default the bottom of an image is aligned with the text as shown in this paragraph.
parameter if you want the viewer to align adjacent text with the top of the image as shown in this paragraph. The full inline image tag with the top alignment is:
<IMG ALIGN=top SRC="filename.GIF">If you have a larger image (i.e., one that fills most of your screen), you should insert an end of paragraph tag (
<p>) before inserting the image parameter. End with another paragraph tag. (Or you might want to have the image open a new window, which is explained below.)
To include a reference to a graphic in an external document, use
<A HREF = "filename.gif">link anchor</A>Make certain the image is in GIF, TIFF, JPEG, RGB, or HDF format.
<img>tag points at an image that does not exist or cannot be otherwise obtained from whatever server is supposed to be serving it, the NCSA logo is substituted. For example, entering
<img href="DoesNotExist.gif">(where "DoesNotExist.gif" is a nonexistant file) causes the following to be displayed:
<TITLE>A Longer Example</TITLE> <H1>A Longer Example</H1> This is a simple HTML document. This is the first paragraph. <P> This is the second paragraph, which shows special effects. This is a word in <I>italics</I>. This is a word in <B>bold</B>. Here is an inlined GIF image: <IMG SRC="myimage.gif">. <p> This is the third paragraph, which demonstrates links. Here is a hypertext link from the word <A HREF="subdir/myfile.html">foo</A> to a document called "subdir/myfile.html". <P> (If you try to follow this link, you will get an error screen.) <H2>A second-level header</H2> Here is a section of text that should display as a fixed-width font: <P> <PRE> On the stiff twig up there Hunches a wet black rook Arranging and rearranging its feathers in the rain ... </PRE> This is a unordered list with two items: <P> <UL> <LI> cranberries <LI> blueberries </UL> This is the end of my example document. <P> <address>Me (firstname.lastname@example.org)</address>________________________________________________________________________ Click here to see the formatted version.
For More Information
on HTML is available through the following hyperlinks.
____________________________________________________________________A Beginner's Guide to HTML/ NCSA / email@example.com