When a backup copy is available, the Edit Text page will offer to Edit Copy. This link goes to a special editor.
This is not one of them.
Go forward to the page you want to change.
Scroll all the way to the top.
Use the hyperlink there to get the right Edit Text page.
Now, if a backup copy is available, you can ...
Scroll to the top of this page.
Use the Edit Copy hyperlink to edit the original copy.
You may want to read More About Backup Copies first.
If you just want to see what the last person changed, click on the last changed date/time instead: It will give you a Quick Diff, showing colored differences.
This site is now keeping additional history beyond that offered by Edit Copy. Volunteers who take care of the occasional lost page will find some old pages stored in plain text at c2.com 
. I intend to limit their retention to only a few days. -- Ward Cunningham
(Note that at present tabs in the original page become whitespace in the history version.)
Yikes. You're right, although this must happen at the browser. I was able to get a tabbed version by simply asking my browser to save the page to a file. -- Ward Cunningham
See original on c2.com