Original: In 2004, with the ratification of the full 802.11 i standard (i.e. WPA2), the IEEE declared that both WEP-40 and WEP-104 "have been deprecated as they fail to meet their security goals".
Simplified: It was part of the full 802.11 i standard (also known as WPA2), the IEEE declared that both WEP-40 and WEP-104 "have been deprecated as they fail to meet their security goals".