Mi sono accorto della stessa cosa. Pagine già validate, oggi non lo sono più. Cambia, se nella doctype si mette XHTML 1.0 Strict//EN (valida) o XHTML 1.1 Strict//E N (non valida) con questo errore
codice:
Error Line 8 column 73: character data is not allowed here.
...e" content="text/html; charset=iso-8859-1" />
You have used character data somewhere it is not permitted to appear.
Mistakes that can cause this error include putting text directly in
the body of the document without wrapping it in a container element
(such as a
aragraph</p>) or forgetting to quote an attribute value
(where characters such as "%" and "/" are common, but cannot appear
without surrounding quotes).
codice:
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />