1<!-- beginners.html -->
2<HEAD>
3<TITLE> A Beginner's Guide to HTML </TITLE>
4<BODY>
5
6
7<H1>A Beginner's Guide to HTML
8
9</H1>This is a primer for producing documents in HTML, the markup language used by the World Wide Web.
10
11<UL>
12<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Acronyms" NAME=14>Acronym expansion - the World Wide Web alphabet soup</A>
13
14<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#MinimalHTML" NAME=15>The minimal HTML document</A>
15<UL>
16<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Titles">Titles</A>
17
18<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Headings">Headings</A>
19
20<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Paragraphs">Paragraphs</A>
21</UL>
22<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Links" NAME=18>Linking to other documents</A>
23<UL>
24<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#URL" NAME=19>Uniform Resource Locator (URL)</A>
25
26<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#NamedAnchorOther" NAME=20>Anchors to specific sections in other documents</A>
27
28<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#NamedAnchorSame" NAME=21>Anchors to specific sections in the same document</A>
29</UL>
30<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#MoreTags" NAME=22>Additional markup tags</A>
31<UL>
32<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Lists" NAME=23>Lists</A>
33<UL>
34<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#UnnumberedLists" NAME=24>Unnumbered lists</A>
35
36<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#NumberedLists" NAME=25>Numbered lists</A>
37
38<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#DescriptiveLists" NAME=26>Descriptive lists</A>
39
40<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#NestedLists" NAME=27>Nested Lists</A>
41</UL>
42<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Preformatted" NAME=28>Preformatted text</A>
43
44<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Blockquote" NAME=29>Extended quotes</A>
45
46<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#CharFormat" NAME=30>Character formatting</A>
47
48<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#SpecialChar" NAME=31>Special characters</A>
49</UL>
50<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#InlineImage" NAME=32>Inline images</A>
51
52<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#ExternalImage" NAME=33>External images</A>
53
54<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Troubleshooting" NAME=34>Troubleshooting</A>
55
56<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#ExtendedExample" NAME=35>A longer example</A>
57
58<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#MoreInfo" NAME=36>For more information</A>
59</UL>
60<A NAME=Introduction>
61<H2 NAME=Introduction>Introduction
62
63</H2>
64</A>
65<A NAME=Acronyms>
66<H3 NAME=Acronyms>Acronym expansion
67
68</H3>
69</A>
70<DL><DT><I>WWW </I>
71<DD>World Wide Web
72<I><DT>SGML </I>
73<DD>Standard Generalized Markup Language - This is perhaps best be thought of as a programming language for style sheets.
74<I><DT>DTD </I>
75<DD>Document Type Definition - This is a specific implementation of document description using SGML. One way to think about this is: Fortran is to a computer program as SGML is to a DTD.
76<I><DT>HTML </I>
77<DD>HyperText Markup Language - HTML is a SGML DTD. In practical terms, HTML is a collection of styles used to define the various components of a World Wide Web document.
78<DT>
79<DD>
80</DL>
81<A NAME=NotCovered>
82<H3 NAME=NotCovered>What this primer doesn't cover
83
84</H3>
85</A>This primer assumes that you have:
86
87<UL>
88<LI> at least a passing knowledge of how to use NCSA Mosaic or other WWW browser
89
90<LI> a general understanding of how World Wide Web servers and client browsers work and
91
92<LI> access to a World Wide Web server for which you would now like to produce HTML documents
93</UL>
94<A NAME=CreatingHTML>
95<H3 NAME=CreatingHTML>Creating HTML documents
96
97</H3>
98</A>HTML documents are in plain text format and can be created using any text editor (e.g., Emacs or vi on Unix machines). A couple of WWW browsers (tkWWW for X Window System machines and CERN's WWW browser for the NeXT) do include rudimentary HTML editors in a WYSIWYG environment, and you may want to try one of them first before delving into the details of HTML.
99
100<P>
101
102<I>You can preview documents in progress with NCSA Mosaic (and some other WWW browers). Open the document using the Open Local option under the
103<B>File
104</B> 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
105<B>Reload
106</B> button on the bottom menu. The edits are reflected in the on-screen display.
107
108<P>
109
110</I>
111<A NAME=MinimalHTML>
112<H2 NAME=MinimalHTML>The minimal HTML document
113
114</H2>
115</A>Here is a barebones example of HTML:
116
117<P>
118____________________________________________________________________
119
120<PRE>
121  &lt;TITLE&gt;The simplest HTML example&lt;/TITLE&gt;
122
123  &lt;H1&gt;This is a level one heading&lt;/H1&gt;
124
125  Welcome to the world of HTML.
126  This is one paragraph.&lt;P&gt;
127
128  And this is a second.&lt;P&gt;
129
130</PRE>____________________________________________________________________
131
132
133<A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/MinimalHTML.html" NAME=10>Click here
134</A> to see the formatted version of the example.
135
136<P>
137HTML uses
138<DFN>tags
139</DFN> to tell the World Web viewer how to display the text. The above example uses
140
141<UL>
142<LI> the <CODE>&lt;TITLE&gt;</CODE> tag (which has a correspondinging <CODE>&lt;/TITLE&gt;</CODE> tag), which specifies the title of the document,
143
144<LI> the <CODE>&lt;H1&gt;</CODE> header tag (with corresponding <CODE>&lt;/H1&gt;</CODE>), and
145
146<LI> the <CODE>&lt;P&gt;</CODE> end-of-paragraph tag.
147</UL>HTML tags consist of a left angular bracket (
148<CODE>&lt;
149</CODE>), known as a ``less than'' symbol to mathematicians, followed by some text (called the
150<DFN>directive
151</DFN>) and closed by a right angular bracket (
152<CODE>&gt;
153</CODE>). Tags are usually paired, e.g.
154<CODE>&lt;H1&gt;
155</CODE> and
156<CODE>&lt;/H1&gt;
157</CODE>. The ending tag looks just like the starting tag except a slash (/) precedes the text within the brackets. In the example,
158<CODE>&lt;H1&gt;
159</CODE> tells the viewer to start formatting a top level heading;
160<CODE>&lt;/H1&gt;
161</CODE> tells the viewer that the heading is complete.
162
163<P>
164The primary exception to the pairing rule is the
165<CODE>&lt;P&gt;
166</CODE> end-of-paragraph tag. There is no such thing as
167<CODE>&lt;/P&gt;
168</CODE>.
169
170<P>
171
172<STRONG>Note:
173</STRONG> HTML is
174<EM>not
175</EM> case senstive.
176<CODE>&lt;title&gt;
177</CODE> is completely equivalent to
178<CODE>&lt;TITLE&gt;
179</CODE> or
180<CODE>&lt;TiTlE&gt;
181</CODE>.
182
183<P>
184Not all tags are supported by all World Wide Web browsers. If a browser does not support a tag, it should just ignore it, though.
185
186<P>
187
188<A NAME=Titles>
189<H3 NAME=Titles>Titles
190
191</H3>
192</A>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.
193<I>In NCSA Mosaic, the Document Title field is at the top of the screen just below the pulldown menus.
194
195<P>
196
197</I>The directive for the title tag is
198<CODE>&lt;title&gt;
199</CODE>. The title generally goes on the first line of the document.
200
201<P>
202
203<A NAME=Headings>
204<H3 NAME=Headings>Headings
205
206</H3>
207</A>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
208<CODE>&lt;H1&gt;
209</CODE>. The syntax of the heading tag is:
210
211<PRE>
212  &lt;H<VAR>y </VAR>&gt;<VAR>Text of heading </VAR>&lt;/H<VAR>y </VAR>&gt;
213
214<P>
215</PRE>where
216<VAR>y
217</VAR> is a number between 1 and 6 specifying the level of the heading.
218
219<P>
220For example, the coding for the ``Headings'' section heading above is
221
222<PRE>
223  &lt;H3&gt;Headings&lt;/H3&gt;
224
225</PRE>
226<STRONG>Title versus first heading
227</STRONG>: 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).
228
229<P>
230
231<A NAME=Paragraphs>
232<H3 NAME=Paragraphs>Paragraphs
233
234</H3>
235</A>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. Notice that in the barebones example, the first paragraph is coded as
236
237<P>
238
239<PRE>
240  Welcome to HTML.
241  This is the first paragraph. &lt;P&gt;
242
243</PRE>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
244<CODE>&lt;P&gt;
245</CODE> tag.
246
247<P>
248
249<STRONG>Important:
250</STRONG> You must end each paragraph with
251<CODE>&lt;P&gt;
252</CODE>. The viewer ignores any indentations or blank lines in the source text. Without the
253<CODE>&lt;P&gt;
254</CODE> 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
255<A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html#Preformatted" NAME=12>below
256</A>.) For instance, the following would produce identical output as the first barebones HTML example:
257
258<P>
259________________________________________________________________________
260
261<PRE>
262  &lt;TITLE&gt;The simplest HTML example&lt;/TITLE&gt;&lt;H1&gt;This is a level
263  one heading&lt;/H1&gt;Welcome to the world of HTML. This is one
264  paragraph.&lt;P&gt;And this is a second.&lt;P&gt;
265
266</PRE>________________________________________________________________________
267
268However, to preserve readability in HTML files, headings should be on separate lines, and paragraphs should be separated by blank lines.
269
270
271<A NAME=Links>
272<H2 NAME=Links>Linking to other documents
273
274</H2>
275</A>The chief power of HTML comes from its ability to
276<DFN>link
277</DFN> regions of text (and also images) to another document (or an image). These regions are typically highlighted by the browser to indicate that they are hypertext links.
278<I>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.
279</I>HTML's single hypertext-related directive is
280<CODE>A
281</CODE>, which stands for anchor. To include anchors in your document:
282
283<P>
284
285<OL>
286<LI> Start by opening the anchor with the leading angle bracket and the anchor directive followed by a space: <CODE>&lt;a</CODE>
287
288<LI> Specify the document that's being pointed to by giving the parameter <CODE>href="filename.html" </CODE>followed by a closing angle bracket: <CODE>&gt;</CODE>
289
290<LI> Enter the text that will serve as the hypertext link in the current document (i.e., the text that will be in a different color and/or underlined)
291
292<LI> Enter the ending anchor tag: <CODE>&lt;/A&gt;</CODE>
293</OL>Below is an sample hypertext reference:
294
295<P>
296
297<PRE>
298  &lt;a href="MaineStats.html"&gt;Maine&lt;/a&gt;
299
300</PRE>This entry makes ``Maine'' the hyperlink to the document
301<SAMP>MaineStats.html
302</SAMP>.
303
304<P>
305
306<A NAME=URL>
307<H3 NAME=URL>Uniform Resource Locator
308
309</H3>
310</A>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:
311
312<P>
313
314<PRE>
315<VAR>scheme </VAR>://<VAR>host.domain </VAR>[:<VAR>port </VAR>]/<VAR>path </VAR>/<VAR>filename </VAR>
316
317<P>
318</PRE>where
319<DFN>scheme
320</DFN> is one of:
321
322<DL><DT><CODE>file</CODE>
323<DD>a file on your local system, or a file on an anonymous ftp server
324<CODE><DT>http</CODE>
325<DD>a file on a World Wide Web server
326<CODE><DT>gopher</CODE>
327<DD>a file on a Gopher server
328<CODE><DT>WAIS</CODE>
329<DD>a file on a WAIS server
330</DL>The scheme can also be
331<CODE>news
332</CODE> or
333<CODE>telnet
334</CODE>, but these are used much less often than the above. The port number can generally be omitted from the URL.
335
336<P>
337For example if you wanted to insert a link to this primer, you would insert
338
339<PRE>
340  &lt;A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html"&gt;
341  NCSA's HTML Primer&lt;/A&gt;
342
343</PRE>into your document. This would make the text ``NCSA's HTML Primer'' a hyperlink leading to this document.
344
345Refer to the
346<A HREF="http://info.cern.ch/hypertext/WWW/Addressing/Addressing.html">Addressing
347</A> document prepared by CERN for additional information about URLs.
348<CITE>A Beginner's
349<A HREF="http://www.ncsa.uiuc.edu/demoweb/url-primer.html">Guide
350</A> to URLs
351</CITE> is located on the NCSA Mosaic Help menu.
352
353<P>
354
355<A NAME=NamedAnchorOther>
356<H3 NAME=NamedAnchorOther>Anchors to Specific Sections in Other Documents
357
358</H3>
359</A>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
360<DFN>named anchor
361</DFN> in document B. For example, to add an anchor named ``Jabberwocky" to document B, you would insert
362
363<PRE>
364  Here's &lt;A NAME="Jabberwocky"&gt;some text&lt;/a&gt;.
365
366</PRE>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(``#''):
367
368<PRE>
369    This is my &lt;A HREF="documentB.html#Jabberwocky"&gt;link&lt;/a&gt;.
370
371</PRE>Now clicking on the word ``link'' in document A would send the reader directly to the words ``some text'' in document B.
372<A NAME=NamedAnchorSame>
373
374<H3 NAME=NamedAnchorSame>Anchors to Specific Sections within the Current Document
375
376</H3>
377</A>The technique is exactly the same except the file name is now omitted.
378
379<P>
380
381<STRONG>Note:
382</STRONG> The NCSA Mosaic
383<B>Back
384</B> button does not work for an anchor within a document because the
385<B>Back
386</B> button is designed to move to a previous document. Move back manually within the document using the scroll bar. (The
387<B>Back
388</B> button will return to the start of a hyperlink effective with Version 2.0 of NCSA Mosaic.)
389
390<P>
391
392<A NAME=MoreTags>
393<H2 NAME=MoreTags>Additional markup tags
394
395</H2>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.
396</A>
397<A NAME=Lists>
398
399<H3 NAME=Lists>Lists
400
401</H3>
402</A>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.
403<A NAME=UnnumberedLists>
404
405<H4 NAME=UnnumberedLists>Unnumbered Lists
406
407</H4>
408</A>
409<OL>
410<LI> Start with an opening list <CODE>&lt;ul&gt;</CODE> tag.
411
412<LI> Enter the <CODE>&lt;li&gt;</CODE> tag followed by the individual item. (Remember that no closing tag is needed.)
413
414<LI> End with a closing list <CODE>&lt;/ul&gt;</CODE> tag.
415</OL>Below an example two-item list:
416
417<P>
418
419<PRE>
420  &lt;UL&gt;
421  &lt;LI&gt; apples
422  &lt;LI&gt; bananas
423  &lt;/UL&gt;
424
425</PRE>The output is:
426
427
428<UL>
429<LI> apples
430
431<LI> bananas
432</UL>
433<P>
434
435<P>
436Note that different viewers display an unordered list differently. A viewer might use bullets, filled circles, or dashes to show the items.
437
438<P>
439
440<A NAME=NumberedLists>
441<H4 NAME=NumberedLists>Numbered Lists
442
443</H4>
444</A>A numbered list (also called an ordered list, from where the abbreviation comes) uses the
445<CODE>&lt;ol&gt;
446</CODE> directive to start a list rather than the
447<CODE>&lt;ul&gt;
448</CODE> directive. The items are tagged using the same
449<CODE>&lt;li&gt;
450</CODE> tag as for a bulleted list. For example:
451
452<P>
453
454<PRE>
455  &lt;OL&gt;
456  &lt;LI&gt; oranges
457  &lt;LI&gt; peaches
458  &lt;LI&gt; grapes
459  &lt;/OL&gt;
460
461</PRE>The list looks like this online:
462
463
464<OL>
465<LI> oranges
466
467<LI> peaches
468
469<LI> grapes
470</OL>
471<P>
472
473<P>
474
475<A NAME=DescriptiveLists>
476<H4 NAME=DescriptiveLists>Descriptive Lists
477
478</H4>
479</A>A description list usually consists of alternating a
480<DFN>description title
481</DFN> (abbreviated as dt) and a
482<DFN>description description
483</DFN> (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.
484
485<P>
486Below is an example description list as included in your source file:
487
488<P>
489
490<PRE>
491  &lt;DL&gt;
492  &lt;DT&gt; National Center for Supercomputing Applications
493  &lt;DD&gt; NCSA is located on the campus of the University
494  of Illinois at Urbana-Champaign. NCSA is a one of
495  four member institutions in the National Metacenter for
496  Computational Science and Engineering.
497  &lt;DT&gt; Cornell Theory Center
498  &lt;DD&gt; CTC is located on the campus of Cornell
499  University in Ithaca, New York. CTC is another member
500  of the National Metacenter for  Computational Science
501  and Engineering.
502  &lt;/DL&gt;
503
504</PRE>The output looks like this:
505
506
507<DL><DT>National Center for Supercomputing Applications
508<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.
509<DT>Cornell Theory Center
510<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.
511</DL>The
512<CODE>&lt;DT&gt;
513</CODE> and
514<CODE>&lt;DD&gt;
515</CODE> entries can contain multiple paragraphs (separated by paragraph tags), lists, or other description information.
516
517<P>
518
519<A NAME=NestedLists>
520<H4 NAME=NestedLists>Nested Lists
521
522</H4>
523</A>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.
524
525<P>
526Remember 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.
527<I>NCSA Mosaic indents the second level in the following list and changes the ``bullet'' from a bullet to a small box.
528
529<P>
530
531</I>An example nested list:
532
533<P>
534
535<PRE>
536  &lt;UL&gt;
537  &lt;LI&gt; A few New England states:
538    &lt;UL&gt;
539    &lt;LI&gt; Vermont
540    &lt;LI&gt; New Hampshire
541    &lt;/UL&gt;
542  &lt;li&gt; One Midwestern state:
543    &lt;UL&gt;
544    &lt;LI&gt; Michigan
545    &lt;/UL&gt;
546  &lt;/UL&gt;
547
548</PRE>The nested list is displayed as
549
550
551<UL>
552<LI> A few New England states:
553<UL>
554<LI> Vermont
555
556<LI> New Hampshire
557</UL>
558<LI> One Midwestern state:
559<UL>
560<LI> Michigan
561</UL>
562</UL>
563<A NAME=Preformatted>
564<H3 NAME=Preformatted>Preformatted Text
565
566</H3>
567</A>Use the
568<CODE>pre
569</CODE> tag (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:
570
571<P>
572
573<PRE>
574&lt;PRE&gt;
575  #!/bin/csh
576  cd $SCR
577  cfs get mysrc.f:mycfsdir/mysrc.f
578  cfs get myinfile:mycfsdir/myinfile
579  fc -02 -o mya.out mysrc.f
580  mya.out
581  cfs save myoutfile:mycfsdir/myoutfile
582  rm *
583&lt;/PRE&gt;
584
585</PRE>display as:
586
587<PRE>
588  #!/bin/csh
589  cd $SCR
590  cfs get mysrc.f:mycfsdir/mysrc.f
591  cfs get myinfile:mycfsdir/myinfile
592  fc -02 -o mya.out mysrc.f
593  mya.out
594  cfs save myoutfile:mycfsdir/myoutfile
595  rm *
596
597</PRE>Hypertext references (and other HTML tags) can be used within &lt;pre&gt; sections.
598<A NAME=Blockquote>
599
600<H3 NAME=Blockquote>Extended quotes
601
602</H3>
603</A>Use the
604<CODE>&lt;blockquote&gt;
605</CODE> and
606<CODE>&lt;/blockquote&gt;
607</CODE> tags to include quotations in a separate block on the screen.
608
609<P>
610For example
611
612<PRE>
613  &lt;blockquote&gt;
614  Let us not wallow in the valley of despair. I say to you, my
615  friends, we have the difficulties of today and tomorrow. &lt;P&gt;
616
617  I still have a dream. It is a dream deeply rooted in the
618  American dream. &lt;P&gt;
619
620  I have a dream that one day this nation will rise up and
621  live out the true meaning of its creed. We hold these truths
622  to be self-evident that all men are created equal. &lt;P&gt;
623  &lt;/blockquote&gt;
624
625</PRE>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.
626
627I still have a dream. It is a dream deeply rooted in the American dream.
628
629I 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.
630
631
632<A NAME=Addresses>
633<H3 NAME=Addresses>Addresses
634
635</H3>
636</A>The
637<CODE>&lt;ADDRESS&gt;
638</CODE> 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.
639
640<P>
641For example, the last part of the HTML file for this primer is
642
643<PRE>
644  &lt;ADDRESS&gt;
645  A Beginner's Guide to HTML / NCSA / pubs@ncsa.uiuc.edu
646  &lt;/ADDRESS&gt;
647
648</PRE>The result is:
649
650
651<ADDRESS>A Beginner's Guide to HTML / NCSA / pubs@ncsa.uiuc.edu
652
653</ADDRESS>
654<P>
655
656<P>
657
658<A NAME=CharFormat>
659<H3 NAME=CharFormat>Character formatting
660
661</H3>
662</A>Individual words or sentences can be put in special styles.
663<DFN>Logical
664</DFN> styles are those that are configured by your viewer. For example,
665<CODE>&lt;CITE&gt;
666</CODE> may be defined as italic by your viewer. Each time you enter
667<CODE>&lt;CITE&gt;
668</CODE> tags, the viewer automatically displays the text in italics.
669
670<P>
671A
672<DFN>physical
673</DFN> style is one that you determine, and the viewer displays what you have coded. For example
674<CODE>&lt;I&gt;
675</CODE> tells the viewer to display your text in italics.
676
677<P>
678For HTML-coded documents, you should use logical styles whenever possible. Future implementations of HTML may not implement physical styles at all.
679
680<P>
681
682<UL>
683<LI> Italic
684<UL>
685<LI> <CODE>&lt;I&gt;text&lt;/i&gt;</CODE> puts text in italics (<I>HTML Primer </I>)
686
687<LI> <CODE>&lt;em&gt;text&lt;/em&gt;</CODE> also italicizes text (only <EM>one</EM> viewer)
688
689<LI> <CODE>&lt;cite&gt;text&lt;/cite&gt;</CODE> is used for citations of names of manuals, sections, or books (<CITE>HTML Primer </CITE>)
690
691<LI> <CODE>&lt;var&gt;text&lt;/var&gt;</CODE> indicates a variable (<VAR>filename </VAR>)
692</UL>
693<LI> Bold
694<UL>
695<LI> <CODE>&lt;b&gt;text&lt;/b&gt;</CODE> puts text in bold (<B>Important</B>)
696
697<LI> <CODE>&lt;strong&gt;text&lt;/strong&gt;</CODE> also emphasizes text (<STRONG>Note:</STRONG>)
698</UL>
699<LI> Fixed width font
700<UL>
701<LI> <CODE>&lt;tt&gt;text&lt;/tt&gt;</CODE> puts text in a fixed-width font (<TT>1 SU = 1 CPU hour</TT>)
702
703<LI> <CODE>&lt;code&gt;text&lt;/code&gt;</CODE> also puts text in a fixed-width font (<CODE>1 SU = 1 CPU hour</CODE>)
704
705<LI> <CODE>&lt;samp&gt;text&lt;/samp&gt;</CODE> formats text for samples (<SAMP>-la</SAMP>)
706
707<LI> <CODE>&lt;kbd&gt;text&lt;/kbd&gt;</CODE> displays the names of keys on the keyboard (<KBD>HELP</KBD>)
708</UL>
709<LI> Other (the following special tag currently does not display in NCSA Mosaic)
710<UL>
711<LI> <CODE>&lt;dfn&gt;text&lt;/dfn&gt;</CODE> displays a definition in italics
712</UL>
713</UL>
714<A NAME=SpecialChar>
715<H3 NAME=SpecialChar>Special Characters
716
717</H3>
718</A>Three
719<A NAME=characters>characters
720</A> out of the entire ASCII (or ISO 8859) character set are
721<I>special
722</I> and cannot be used ``as-is'' within an HTML document. These characters are left angle bracket (
723<CODE>&lt;
724</CODE>), right angle bracket (
725<CODE>&gt;
726</CODE>), and ampersand (
727<CODE>&
728</CODE>).
729
730<P>
731The 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:
732
733<UL>
734<LI> <CODE>&lt;</CODE> is the <I>escape sequence </I> for <CODE>&lt;</CODE>
735
736<LI> <CODE>&gt;</CODE> is the escape sequence for <CODE>&gt;</CODE>
737
738<LI> <CODE>&amp;</CODE> is the escape sequence for <CODE>&</CODE>
739</UL>Note that ``escape sequence'' means that the given sequence of characters represents the single character in an HTML document and that the semicolon is required. The conversion to the single character itself takes place when the document is formatted for display by a reader.
740
741<P>
742There are additional escape sequences, such as a whole set of sequences to support 8-bit character sets (ISO 8859-1). For example:
743
744<UL>
745<LI> <CODE>&ouml;</CODE> is the escape sequence for a lowercase <CODE>o</CODE> with an umlaut: �
746
747<LI> <CODE>&ntilde;</CODE> is the escape sequence for a lowercase <CODE>n</CODE> with an tilde: �
748
749<LI> <CODE>&Egrave;</CODE> is the escape sequence for an uppercase <CODE>E</CODE> with a grave mark: �
750</UL>Many such escapes exist and are available in a
751<A HREF="http://info.cern.ch/hypertext/WWW/MarkUp/ISOlat1.html" NAME=2>listing
752</A> from CERN.
753
754<P>
755
756<A NAME=InlineImage>
757<H2 NAME=InlineImage>Inline Images
758
759</H2>
760</A>NCSA Mosaic is can display X Bitmap (XBM) or GIF format images inside documents.
761<I>Each image takes time to process and slows down the initial display of the document
762</I>. Using a particular image multiple times in a document causes very little performance degradation compared to using the image only once.
763
764<P>
765
766<B>NOTE:
767</B> The
768<CODE>&lt;img&gt;
769</CODE> tag is an HTML extension first implemented in NCSA Mosaic. Currently it is not understood by most other World Wide Web browsers.
770
771<P>
772To include an inline image in your document, enter:
773
774<P>
775
776<PRE>
777    &lt;IMG SRC="filename.GIF"&gt;
778
779</PRE>
780
781
782<IMG>?
783By default the bottom of an image is aligned with the text as shown in this paragraph.
784
785<P>
786
787<IMG>?
788Include the
789<CODE>align=top
790</CODE> 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:
791
792<PRE>
793    &lt;IMG ALIGN=top SRC="filename.GIF"&gt;
794
795</PRE>
796
797If you have a larger image (i.e., one that fills most of your screen), you should insert an end of paragraph tag (
798<CODE>&lt;p&gt;
799</CODE>) 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.)
800<A NAME=ExternalImage>
801
802<H3 NAME=ExternalImage>External Images
803
804</H3>
805</A>You may want to have an image open as a separate document when a user activates a link on either a word or a smaller version of the image that you have inlined into your document. This is considered an external image and is particularly useful because (assuming you use a word for your hypertext link) you do not have any processing time degradation in the main document. Even if you include a small image in your document as the hyperlink to the larger image, the processing time for the ``postage stamp'' image is less than the full image.
806
807<P>
808To include a reference to a graphic in an external document, use
809
810<PRE>
811    &lt;A HREF = "filename.gif"&gt;link anchor&lt;/A&gt;
812
813</PRE>
814
815Make certain the image is in GIF, TIFF, JPEG, RGB, or HDF format.
816<A NAME=Troubleshooting>
817
818<H2 NAME=Troubleshooting>Troubleshooting
819
820</H2>
821</A>
822<UL>
823<LI> While certain HTML constructs can be nested (for example, you can have an anchor within a header), they cannot be overlapped. For example, the following is <I>invalid </I> HTML:
824<PRE>
825
826<LI> is &lt;a name="foo"&gt;invalid HTML.&lt;/h1&gt;&lt;/a&gt;
827
828</PRE>
829<LI> many current HTML parsers aren't very good at handling invalid HTML, avoid overlapping constructs.
830
831
832<LI> In NCSA Mosaic, when an <CODE>&lt;img&gt;</CODE> 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 <CODE>&lt;img href="DoesNotExist.gif"&gt; </CODE>(where "DoesNotExist.gif" is a nonexistant file) causes the following to be displayed: <IMG>?
833
834
835<LI> this happens to you, first make sure that the referenced image does in fact exist and that the hyperlink has the correct information in the link entry. Next verify that the file permission is set appropriately (world-readable).
836</UL>
837<A NAME=ExtendedExample>
838<H2 NAME=ExtendedExample>A Longer Example
839
840</H2>
841</A>Here is a longer example of a HTML document:
842
843<P>
844________________________________________________________________________
845
846<PRE>
847  &lt;TITLE&gt;A Longer Example&lt;/TITLE&gt;
848  &lt;H1&gt;A Longer Example&lt;/H1&gt;
849
850  This is a simple HTML document. This is the first
851  paragraph. &lt;P&gt;
852
853  This is the second paragraph, which shows special effects.  This is a
854  word in &lt;I&gt;italics&lt;/I&gt;.  This is a word in &lt;B&gt;bold&lt;/B&gt;.
855  Here is an inlined GIF image: &lt;IMG SRC="myimage.gif"&gt;.
856  &lt;p&gt;
857
858  This is the third paragraph, which demonstrates links.  Here is
859  a hypertext link from the word &lt;A HREF="subdir/myfile.html"&gt;foo&lt;/A&gt;
860  to a document called "subdir/myfile.html". &lt;P&gt;  (If you
861  try to follow this link, you will get an error screen.)
862
863  &lt;H2&gt;A second-level header&lt;/H2&gt;
864
865  Here is a section of text that should display as a
866  fixed-width font: &lt;P&gt;
867
868  &lt;PRE&gt;
869      On the stiff twig up there
870      Hunches a wet black rook
871      Arranging and rearranging its feathers in the rain ...
872  &lt;/PRE&gt;
873
874  This is a unordered list with two items: &lt;P&gt;
875
876  &lt;UL&gt;
877  &lt;LI&gt; cranberries
878  &lt;LI&gt; blueberries
879  &lt;/UL&gt;
880
881  This is the end of my example document. &lt;P&gt;
882
883  &lt;address&gt;Me (me@mycomputer.univ.edu)&lt;/address&gt;
884
885</PRE>________________________________________________________________________
886
887
888<A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/LongerExample.html" NAME=37>Click here
889</A> to see the formatted version.
890
891<P>
892
893<A NAME=MoreInfo>
894<H2 NAME=MoreInfo>For More Information
895
896</H2>
897</A>More
898<A NAME=information>information
899</A> on HTML is available through the following hyperlinks.
900
901<P>
902
903<UL>
904<LI> <A HREF="http://www.ncsa.uiuc.edu/General/Internet/WWW/Grobe.html">HTML Quick Reference Guide</A>, which gives a comprehensive listing of HTML codes
905
906<LI> the official HTML <A HREF="http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html" NAME=3>specs </A>
907
908<LI> the in-development HTML <A HREF="http://info.cern.ch/hypertext/WWW/MarkUp/HTML.html" NAME=6>RFC</A> (Request for Comments)
909
910<LI> a description of <A HREF="http://info.cern.ch/hypertext/WWW/MarkUp/SGML.html" NAME=4>SGML</A>, the Standard Generalized Markup Language
911
912<LI> the <A HREF="http://info.cern.ch/hypertext/WWW/Addressing/Addressing.html" NAME=5>URL (Uniform Resource Locator) specification</A>
913
914<LI> the <A HREF="http://info.cern.ch/hypertext/WWW/Provider/Style/Overview.html" NAME=8>style guide</A> for online hypertext document structures
915</UL>
916<P>
917
918<P>
919____________________________________________________________________
920
921<ADDRESS>A Beginner's Guide to HTML/ NCSA / pubs@ncsa.uiuc.edu
922</ADDRESS>