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You should enter this web site by using the URL (or alternatively, or If you bookmarked a different URL, please change your bookmarks to one of the above URLs. Any other URL may be temporary, and may change without notice. Individual pages within this site can be reliably bookmarked after entering this site through one of the above URLs.

Please note that parts of this site may be hosted at different Internet locations, and that their geographical locations may change at any time. The URLs above are the only permanent way to reach my web site.


I used to display ads on my pages, albeit not currently - it simply does not generate enough money to have any practical impact, takes space on the pages and is distracting to visitors. If you see any ads on my pages at present (other than in the Google site search pop-up), your ISP is adding them, or you have malware on your computer that does so. Alternatively, you may be visiting my pages through frames of another site. In this case, use one of the above URLs to visit my site instead.

The site search functionality on the home page of this site is provided by Google. Google may choose to display ads and links to sponsored sites in the pop-up that contains the site search results. I have no control over the contents of these ads or their relevance to the contents of this site, and I don't endorse any of the linked sites in these ads.


Updated and changed contents

I usually indicate new pages with a image icon in index pages. Usually, this icon remains until the next major addition of new pages in the same section of the web site. I also update pages whenever new information is available, or whenever I discover errors. Updates happens fairly often for pages of this site, and may range from the correction of misspellings to major additions and/or alterations of contents.

I mark updated pages with an image icon only if the changes are substantial (e.g., major errors have been corrected, or significant materials have been added). The best way for you to know when a page was last updated is to check the "last updated" file date in the footer of each page. This is actually the date the file was last saved on the server, so it may reflect a change in contents, or only cosmetic changes to the layout (for example updates in order to function with current browser versions), or changes of my web authoring tools.


Required web browsers

This web site requires a modern, HTML 5-aware web browser, as well as JavaScript. The code does not function properly without these, and no longer attempts to display a warning if the browser fails to comply with either requirement.

I used to have a couple of Java applets on this site, but continuously changing security requirements and continuously evolving security threats made it too bothersome to keep these applets updated and safe. There are at present no Java applets on this site.

I have tested, and found the current version of this site to work, with Firefox version 78. Other versions and other browsers may work, but have not been tested.

In 2015, I converted this site to a mobile-friendly format.

The appearance of this site is mostly unchanged for visitors using a large screen, but the new layout is simplified with respect to the older one, particularly for what regards illustrations. The visible changes affect mostly users of tablets and smartphones:
dotFigures automatically resize to fit the screen width.
dotFigures are linked to the original image file, to allow viewing at the original size on all devices (this may require scrolling and zooming on small screens).
dotTwo-column and three-column layouts become one-column layouts on small screens.
dotNavigation buttons become larger and more widely spaced on small screens, to allow operating with fingertips.
dotGroups of navigation buttons rearrange on small screens, to avoid horizontal scrolling.
dotNon-essential navigation buttons are hidden to save screen space, and can optionally be displayed with the "Show more" button.
dotSome tables still need horizontal scrolling. This is intentionally done to display the information in a meaningful way.

In this conversion, I followed Google's recommendations for responsive design and verified the web site with Google's webmaster tools.

In 2021, I begun to edit existing pages for better compliance with HTML 5. The process is ongoing. From now on, I only support the HTML 5 standard, and removed all the legacy HTML code that used to support the quirks of older browsers. Gone is also the HTML for browsers that do not support JavaScript (which is now obligatory in HTML 5).

In mid-2021, I finally gave up on using Adobe Dreamweaver templates. All traces of Dreamweaver templates should be gone from the HTML code. The Dreamweaver template functionality, which I started using in version 6, has become more and more broken during the years, and in version 21 I find it unusable because it crashes Dreamweaver every time I try to use it, occasionally corrupting HTML files. This function apparently cannot cope with parts of HTML code that have nothing to do with templates, in spite of the code passing Dreamweaver's HTML validation as well as external validation tools. Adobe has been aware of the problem for many years, but refused to fix it in spite of frequent reports by users on Adobe's own support site.

Among several other complaints I have about Dreamweaver, its automatic HTML formatting feature is also flaky. The configurable settings work with some tabs, but not with others. For example, the configurable formatting for the <tr> tag is also applied to the </tr> tag (which is what I expect), but the configurable formatting for the <td> tab is not applied to </td>, which is annoying. Same thing with the <script> and </script> tags. Nested <span> tags pass HTML 5 validation, but the WYSIWYG editor most of the time does not want to insert them for me. Since I have the nasty habit of visually inspecting the automatically generated HTML, I am also aware of the need to manually remove the various oddities randomly inserted by the Dreamweaver WYSIWYG editor.

Site history

I started this web site in 1990, hosting it on a Windows PC under my desk in my university office. It is currently hosted by a US-based web provider and its contents are in accordance to and protected by US laws (in particular, by their strong protection of freedom of expression). I am physically resident in Sweden, which grants a similar freedom of expression.

This web site was hacked just once, on May 17, 2000 (when it was running under Microsoft IIS on another host). The home page was substituted with this. For a free, and more reliable, multi-platform alternative to Microsoft Internet Information Services, see the Apache web server.

Over 10 years ago I stopped using my own web server, and since then I have been running this web site on servers provided by hosting companies in the United States.

Judging from web hit counters, visitors of this web site are primarily located in the United States, with lesser numbers from China, Japan and Australia, and a smattering from other countries including even the least likely places on Earth. Visits from EU countries are logged by the individual country. Added together, EU visitors usually come in first or second place.

Hardening against hacking

This web site contains only static HTML pages, so it is extremely unlikely that hackers will find anything interesting to do here. There are no databases and no web CMS to break into, no web application to break, no user comments or bulletin board to harvest or troll, no way to upload anything through the web interface, and no server-side languages to exploit. Just plain old HTML and client-side Javascript.

All content creation, templating and styling is done offline at a remote location before uploading the HTML to the server. If a hacker should succeed in altering or deleting this web site, I can simply upload an exact copy of the original within minutes on this or another web server.


See cookie policy.

Ad blockers

This site will never ask you to switch off your ad blocker. In fact, I do recommend that you always use an ad blocker on any web site, period. Ads should be rellay optional, not something being forced down your throat whether you want them or not. I stopped visiting some web sites I used on a regular basis, when their insistance on switching off my ad blocker ads became too much for me, and I will continue to do so in the future. I do appreciate that the publishers of web sites do need to put food on their tables, but do not accept that they do so by forcing ads on me. If they believe that the contents of their web sites are really that desirable, they should consider selling access subscriptions instead.

Using an ad blocker on this site makes no difference because there are no ads on this site (with the possible exception of sponsored links on the Google search results page, which is generated by Google).

I do wholeheartedly support the idea of untraceable ad blockers. The technology is entirely feasible, and not that complicated.

The law

In accordance with EU law, I can link to your (or any other) publicly accessible web site without asking your permission and regardless of whether the materials I am linking to are copyrighted. Cross-linking to images and other media on another site to make it appear as a part of the linking site is explicitly allowed by EU law, regardless of whether the link target is copyrighted.

For example, I am allowed to link to a picture on your web site and present the picture to a visitor of my web site to make it appear like the picture is a part of my web site. I rarely do this, and only with good reasons. I always add a link to the picture that leads back to the original source or web site of the picture. However, be advised that I am under no legal obligation to do this.

Many other countries or states have similar laws.

I choose which links to other sites to publish on this site, based on a single criterion:

  • I link to web sites that I personally find to be useful in the context of a specific discussion on my site.
    • I am aware that millions of web sites are useful in a general sense, but I am not in the business of compiling and maintaining a list of web sites useful to the general public.
    • I am also aware that the web contents I find useful may be too simple or too complex to be interesting to others, and vice versa.
    • In special cases, I may publish non-clickable URLs to specific web sites to warn others against visiting these sites

Please also note:

  • I do not engage in link swaps (i.e., you link to my site, and I link to yours in return)
    • I make no money from visitors of this web site, and I am under no pressure to increase the number of visitors of my web site.
    • Google is more than good enough to draw a sufficient number of visitors to this site.
    • I am satisfied with my site only being visited by people who are interested in the contents I provide.

You are free to link to my web site, or to specific pages or materials on my web site, as you see fit. You do not need my permission to link to my site. However, please note:

  • URLs on my site may change without notice. It rarely happened so far, but I might be forced to do this in the future, for example if I will find it necessary to restructure my site or delete obsolete information.
  • Linking to my web site does not imply that I will link to your site in return.
    • I will link to your site only if I have a reason to (as explained above), and regardless of whether you link to my site.

Distribution of page hits (whole site) during the last month.
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This site is ad-free. If you see any ads here, they are added by your ISP, or by spyware on your computer, or you are visiting this site through frames of another site.