Accessibility Statement

If you have any questions or comments about this page, or about the accessibility of this site, please don't hesitate to contact the webmaster.

Standards Compliance

These pages are written in XHTML 1.1, and served as application/xhtml+xml to compatible browsers. Equations are written in MathML 2.0. Wherever possible, figures are prepared in SVG 1.0, with a fallback to a GIF image. Styling is done using CSS 2. It goes without saying that all of the above validate.

These pages are Section 508 approved, complying with the U.S. Federal Government Section 508 Guidelines. They also comply with all Priority 1 (but see below) and most Priority 2,3 checkpoints of the W3C Web Content Accessibility Guidelines.


Most browsers support navigation using keyboard shortcuts called AccessKeys, defined by the website you're visiting. On Windows, you can press Alt + an AccessKey; on a Macintosh, you can press Control + an AccessKey. The Opera browser takes a different approach: you press Shift +ESC and then the AccessKey. Please note that in Internet Explorer for Windows, if the AccessKey refers to another page, pressing Alt + an AccessKey will only shift focus to the link. You must then press Return to follow the link. In Windows, Alt + some key is also used for menu shortcuts. If one of my AccessKeys is usurping a menu shortcut of yours, you can always access the menu shortcut by typing Alt then the key.

The following AccessKeys are defined:

Accessibility Statement
Main Page
Skip to Content
List of Posts
Previous (individual/monthly archive page)
Next (individual/monthly archive page)

If you have Javascript enabled, you can customize these AccessKey mappings using the edit button which will be visible in the footer of any page on this site (including this one). You can assign any keyboard character you want to an AccessKey, however most browsers ignore the distinction between uppercase and lowercase letters. If you want to disable one (or all) of the AccessKeys, delete the corresponding character(s), and then hit save. Your AccessKey mappings will be saved in a cookie, and will be remembered on future visits to this site.

Navigation & Scripting

All individual and monthly archive pages have rel=previous, next, and home links to aid navigation in text-only browsers and ScreenReaders. Mozilla users can also take advantage of this feature by enabling the Site Navigation Bar in the View→Show/Hide→Site Navigation Bar menu. Opera has similar functionality.

All blog pages include a search box (AccessKey-4). Advanced search options are available on the Search Page.

Javascript is used very sparingly. There are no “javascript:” pseudo-links. All links can be followed in any browser, even if scripting is turned off.

Javascript event-handlers, wherever they are used, do not assume you are using a mouse. Both onclick and onkeypress event-handlers are included, so as to accomodate a range of input devices.

With Javascript disabled, the only things you will not be able to do are:

  1. Post comments on this blog. If you cannot enable Javascript, a mailto: link is provided for you to email your comment to the author to post on your behalf.
  2. Customize the AccessKey keybindings, as described above.
  3. Toggle between the "threaded" and "chrononological" views of the comments on a blog entry.

Links that open new windows (such as the comment-entry form) are indicated by a distinctive cursor.

Properly nested headers are used throughout. For example, on pages with more than one day's posts, <h2> tags are used for dates and <h3> tags for individual post titles. JAWS users can skip to the next day using Alt +Insert +2, or to the next post with Alt +Insert +3.

Forms are marked up using the tabindex attribute, so you can navigate through the form fields using the Tab key.

Abbreviations & Acronyms

Abbreviations and acronyms are marked up as an aid to ScreenReaders and other assistive technologies. The definitions are given using the title attribute at their first occurence in each blog post. More details of the methodology and its rationale are given in this post.

Stylesheets & Appearance

The appearance of these pages is controlled by CSS stylesheets. Users, whose browsers support it, can substitute/supplement these by their own stylesheets, to alter the appearance to their liking. A separate print stylesheet is used to provide a more printer-friendly format for printing. An aural stylesheet is provided for those ScreenReaders that support it.

Great effort has been made to maximize the legibilty of these pages. Because the equations have been done in MathML and the figures in SVG, they rescale nicely along with the text, when you use the Text-Zoom feature of your browser. Moreover, with suitable software, MathML equations can be read aloud by ScreenReaders.

Some of the advanced technologies (like MathML or CSS :hover on arbitrary elements) used in these pages are only supported in advanced browsers, like Mozilla. Nonetheless, these pages should be perfectly usable with CSS disabled and in more “primitive” User-Agents, like text-only browsers, ScreenReaders and Internet Explorer.