home  Home      home  ISPRS Foundation      sitemap  Sitemap      search  Search    
June 01, 2020 
Sample Page


Uniform Resource Locators (URLs)

These specify the location of a resource for a hypertext link:







one of...

Internet server hostname
or IP address with optional port.
Email address.
Newsgroup name.

(directory or folder names)

Filename and filetype

? (searching) means
the URL must be a script;
using a # location implies
target label exists.

Note mailto: and news: have no double slash.

Sample document

HTML-code Outlook
    <!-- A sample document --> 
    <TITLE>Document title</TITLE> 
    <H1>Top-level heading</H1> 
    <P>First paragraph of text.</P> 
    <UL> <!-- A bulleted list --> 
      <LI><P>First list item</P></LI> 
      <LI><P>Second list item, with a hypertext 
          <A HREF="../isprs.html">link</A> to another
    <H2>Second-level heading</H2>
    <P>Another paragraph, <IMG ALT="ISPRS logo" 
       ALIGN="bottom" SRC="../images/logo_new_small.gif"> with an
    Last change: 08-Dec-1998 by Markus Englich
Problems and/or queries, send e-mail: <A HREF="mailto:markus.englich@ifp.uni-stuttgart.de"> markus.englich@ifp.uni-stuttgart.de</A> </ADDRESS> </BODY> </HTML>

Top-level heading

First paragraph of text.

  • First list item

  • Second list item, with a hypertext link to another file.

Second-level heading

Another paragraph, ISPRS logo with an illustration.

Last change: 08-Dec-1998 by Markus Englich
Problems and/or queries, send e-mail: markus.englich@ifp.uni-stuttgart.de

HTML quick reference

The HyperText Markup Language (HTML) is composed of a set of elements that define a document and guide its display. This document presents a concise reference guide to HTML, listing the most commonly used elements from Versions 1 and 2 of HTML, and giving a brief description of those elements.

Users should be aware that HTML is an evolving language, and different World-Wide Web browsers may recognize slightly different sets of HTML elements. For general information about HTML including plans for new versions, see external link www.w3.org/hypertext/WWW/MarkUp/MarkUp.html.
For specification of HTML language see
external link www.w3.org/TR/REC-html40/


An HTML element may include a name, some attributes and some text or hypertext, and will appear in an HTML document as

<tag_name> text </tag_name>
<tag_name attribute_name=argument> text </tag_name>, or just
For example:
<title> My Useful Document </title>
<a href="argument"> text </a>
An HTML document is composed of a single element:
<html> . . . </html>
that is, in turn, composed of head and body elements:
<head> . . . </head>
<body> . . . </body>
To allow older HTML documents to remain readable, <html>, <head>, and <body> are actually optional within HTML documents.

Elements usually placed in the head element

Specifies that the current document describes a database that can be searched using the index search method appropriate for whatever client is being used to read the document. For example, a Lynx user will use the "s" keyboard command.
<title> . . . </title>
Specify a document title. Note that the title will not appear on the document as is customary on printed documents. It will usually appear in a window bar identifying the contents of the window. HTML header tags perform the functions usually reserved for titles.
<base href="URL">
Specify the name of the file relative to which partially qualified pathnames in URLs should be interpreted. If not otherwise specified the URL containing the document being displayed is used as the base.
<link rev="RELATIONSHIP" rel="RELATIONSHIP" href="URL">
The link tag allows you to define relationships between the document containing the link tag and the document specified in the "URL". The rel attribute specifies the relationship between the HTML file and the Uniform Resource Locator (URL). The rev attribute (for "reverse") specifies the relationship between the URL and the HTML file. For example, <link rev="made" href="URL"> indicates that the file maker or owner is described in the document identified by the URL. (Note that link tags are not displayed on the screen as part of the document. They define static relationships, not hypertext links.)

Elements usually placed in the body element

The following sections describe elements that can be used in the body of the document.

Text Elements

The end of a paragraph that will be formatted before it is displayed on the screen.
<pre> . . . </pre>
Identifies text that has already been formatted (preformatted) by some other system and must be displayed as is. Preformatted text may include embedded tags, but not all tag types are permitted. The <pre> tag can be used to include tables in documents.
<listing> . . . </listing>
Example computer listing; embedded tags will be ignored, but embedded tabs will work. This is an archaic tag.
<xmp> . . . </xmp>
Similar to <pre> except no embedded tags will be recognized.
Similar to <pre> except no embedded tags will be recognized, and since there is no end tag, the remainder of the document will be rendered as plain text. This is an archaic tag. Note that some browsers actually recognize a </plaintext> tag, even though it is not defined by the standard.
<blockquote> . . . </blockquote>
Include a section of text quoted from some other source.

Hyperlinks or Anchors

<a name="anchor_name"> . . . </a>
Define a target location in a document
<a href="#anchor_name"> . . . </a>
Link to a location in the base document, which is the document containing the anchor tag itself, unless a base tag has been specified.
<a href="URL"> . . . </a>
Link to another file or resource
<a href="URL#anchor_name"> . . . </a>
Link to a target location in another document
<a href="URL?search_word+search_word"> . . . </a>
Send a search string to a server. Different servers may interpret the search string differently. In the case of word-oriented search engines, multiple search words might be specified by separating individual words with a plus sign (+).
An anchor must include a name or href attribute, and may include both. There are several optional attributes, but they are rarely encountered.

The structure of a Uniform Resource Locator (URL) may be expressed as:

where the possible resource types include: file, http, news, gopher, telnet, ftp, and wais, among others, and each resource type relates to a specific server type. Since each server performs a unique function, each resource type requires different additional_information. For example http and gopher URLs will have a structure like:
The colon followed by an integer TCP port number is optional, and is used when a server is listening on a non-standard port.

Strictly speaking, the anchor_name and search_word information included in the name and href attributes in the examples above are part of the URL. They are presented as separate entities for simplicity. A more complete description of URLs is presented in external link http://www.w3.org/hypertext/WWW/Addressing/Addressing.html


<h1> . . . </h1> Most prominent header
<h2> . . . </h2>
<h3> . . . </h3>
<h4> . . . </h4>
<h5> . . . </h5>
<h6> . . . </h6> Least prominent header

Logical Styles

<em> . . . </em>
<strong> . . . </strong>
Stronger emphasis
<code> . . . </code>
Display an HTML directive
<samp> . . . </samp>
Include sample output
<kbd> . . . </kbd>
Display a keyboard key
<var> . . . </var>
Define a variable
<cite> . . . </cite>
Display a citation

Physical Styles

<b> . . . </b>
<i> . . . </i>
<u> . . . </u>
<tt> . . . </tt>
Typewriter font

Definition list/glossary: <dl>

<dt> First term to be defined
<dd> Definition of first term
<dt> Next term to be defined
<dd> Next definition
The <dl> attribute compact can be used to generate a definition list requiring less space.

Present an unordered list: <ul>

<li> First item in the list
<li> Next item in the list

Present an ordered list: <ol>

<li> First item in the list
<li> Next item in the list

Present an interactive menu: <menu>

<li> First item in the menu
<li> Next item

Present a directory list of items: <dir>

<li> First item in the list
<li> Second item in the list
<li> Next item in the list
Items should be less than 20 characters long.


Display a particular character identified by a special keyword. For example the entity &amp; specifies the ampersand ( & ), and the entity &lt; specifies the less than ( < ) character. Note that the semicolon following the keyword is required, and the keyword must be one from the lists presented in: external link http://www.w3.org/pub/WWW/MarkUp/html-spec/html-spec_9.html#SEC9.7
Use a character literally. Again note that the semicolon following the ASCII numeric value is required.


<!-- text -->
Place a comment in the HTML source
<address> . . . </address>
Present address information
<img src="URL" alt="Alternate Text">
Embed a graphic image in the document. Attributes:
Specifies the location of the image.
Allows a text string to be put in place of the image in clients that cannot display images.
Specify a relationship to surrounding text. The argument for align can be one of top, middle, or bottom.
If ismap is present and the image tag is within an anchor, the image will become a "clickable image". The pixel coordinates of the cursor will be appended to the URL specified in the anchor if the user clicks within the ismap image. The resulting URL will take the form "URL?m,n" where m and n are integer coordinates, and the URL will specify the location of a program that will examine the pixel coordinates, and return an appropriate document.
Forces a line break immediately and retains the same style.
Places a horizontal rule or separator between sections of text.

Additional Information

For general information about HTML, see external link http://www.w3.org/TR/html401/

For an HTML Tutorial, see external link http://www.htmlprimer.com/