All images on this site are accompanied by a brief alternative text which where appropriate identifies an image or its function. This alternative text (alt-text) is generally only visible when the browser's automatic image loading feature is turned off.
All text links are written so that they make sense when read out of context.
Most Adobe Acrobat Portable PDF files on this site are tagged to allow basic accessibility.
For more information about PDF accessibility see the Adobe website accessibility section.
For more help with Acrobat files generally and a link to download Acrobat Reader see the site help page.
The text on this website has been styled using a non-fixed value in a style sheet. This means that users can easily change the text size using their browser settings.
Read and translate with Browsealoud
Our website supports Browsealoud. Browsealoud reads web pages aloud for people who find it difficult to read online. It will also translate the text into a number of different languages. The service uses a version of Google Translate which relies on translations already available online – for this reason it may not always be 100% accurate.
For more information and help about changing your browser settings please visit the BBC's My Web My Way pages.
If you any accessibility issues or problems, please contact the online team at email@example.com.