Face-down Defence Position refers to a monster card that is both:
It's DEFENSE
Some monsters (like "Quilbolt Hedgehog") turn blue while in defensive mode in the 5D's anime to further contrast the visual appearances of attack and defense position monsters. Perhaps it was determined that it wasn't enough to show a monster crossing its arm, kneeling, etc.
Yes, this is what you normally do since you can't place them in face down attack position.
The core rules state that a Normal Summon places the monster in face-up Attack position, and a Set places it in face-down Defense position. Special Summons are face-up Attack or Defense position, unless stated otherwise. If the continuous Trap card 'Light of Intervention' is active, monsters can be Normal Summoned in face-up Defense position.
In Yu-Gi-Oh!, when a Defense Position monster is destroyed, damage calculation does not occur. Instead, the monster is sent to the graveyard without involving damage calculation, as it is not in Attack Position. The player does not take any battle damage from the destruction of a Defense Position monster.
Faceup resting position, Facedown Position, and in a ball with a PFD.
If this card attacks a defense position monster your opponent controls, destroy all defense position monsters your opponent controls after damage calculation. During your end phase, destroy all of your monsters that did not declare an attack this turn.
It's DEFENSE
that's a negative, only cards that state their effects in face down defense mode like Big Shield Guardna
1 Tuner + 1 or more non-Tuner monsters If this card attacks a Defense Position monster your opponent controls, destroy all Defense Position monsters your opponent controls after damage calculation. During your End Phase, destroy all other monsters you control that did not declare an attack this turn.
When a monster attacks a defense position monster with DEF equal to to the attacking monster's ATK, no damage is inflicted to either player's Life Points and no monsters are destroyed in battle. Some monsters have effects that activate before or after they battle, so you must take those into account as well.
Defence Mode, or Defence Position, means that the card is placed Horizontally in the monster zone. It could also be Set (face down defence position) or face-up due to being Set and attacked, or switched while face-up from attack to defence.
A business in the defense position is defending its position within its industry. This can happen as a result of new entrants in the industry.
No, if a monster attacks a defense position monster and is then changed to defense position by Kunai with Chain, it cannot be destroyed by battle. In this scenario, the attacking monster is no longer in attack position and thus does not have to compare its attack points to the defense points of the opposing monster. Instead, the battle is resolved in such a way that the attacking monster remains in defense position, and the battle does not result in destruction for either monster.
Some monsters (like "Quilbolt Hedgehog") turn blue while in defensive mode in the 5D's anime to further contrast the visual appearances of attack and defense position monsters. Perhaps it was determined that it wasn't enough to show a monster crossing its arm, kneeling, etc.
Yes, this is what you normally do since you can't place them in face down attack position.
the secretery of defense