By putting a card under another specified card (usually a rear-guard or a set order in the order zone) from the appropriate zone, it becomes that card's gauge.
The zone in which gauge is placed is known as the gauge zone.
The gauge zone under the card is considered to be associated with the card, and will move with the unit between circles.
If a card is put into the gauge zone from a hidden zone, the player can only look at the card after it has been moved to the gauge zone.
The gauge zone is a private zone, as such a player can only view the face down cards of their opponent's gauge zone.
Even if a fighter dominates a unit with a face down gauge, that card's gauge will still be in the opposing player's gauge zone as such cannot be viewed.
When a unit moves to a non-circle zone, or it is locked, all of the gauge associated to it are put into the drop zone.
When referring to a card's gauge, it refers to cards located in the unit's associated gauge zone.
Gauges may have names, and are referred to as "Name" Gauge.
Divine
Equip
Plant
Undercover
AutoMOD
Regress
There is no limit to the number of gauge under a card.
A gauge can also be associated with a player instead of a card, but only if an effect allows for that player to have the specified gauge, such as the effect of the SYSTEM CODE:X-ceed Token.