These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
If your opponent Flip Summons a monster with a Flip Effect, and chains a card like "Offerings to the Doomed" to destroy "Fiend Skull Dragon", the Flip Effect will not be negated since "Fiend Skull Dragon" is no longer on the field when the Flip Effect resolves, and it will only negate Flip Effect "as long as this card remains face-up on the field."
The opponent may activate a Trap Card that targets "Fiend Skull Dragon", but its effect will be negated and the Trap Card destroyed.
Archfiend: "Archfiend" is a special category of card. Most Archfiends can be identified by their name. Any card with "Archfiend" in the card name, is an Archfiend. In addition, several older cards are also considered to be "Archfiends." These cards include: ... Fiend Skull Dragon ...
↑Konami Judge Program Rulings are considered unverified, as their source(s) are not publicly viewable. They are not confirmed as applicable to the TCG until they have been officially published by Konami.