Global lang-attribute validity (validity)

The global language attribute includes a valid language code such as for example, "en", "fr" or "fi" (ISO 639-1 Language Codes)


Invalid lang attribute value:

This page has a lang attribute with an invalid value (lang="Hello world!")

Note: Auto-testing is possible. An auto-test can be performed by programmatically checking if the lang attribute has a valid ISO 639-1 value.