HTML Guide for ISO 639-1
Instead of using the isolang attribute to define the language of the document, you can use lang with an ISO 639-1 two character code.
For example, for Portuguese:
<html lang="pt">Instead of using the isolang attribute to define the language of the document, you can use lang with an ISO 639-1 two character code.
For example, for Portuguese:
<html lang="pt">