'Holding' is the practice of manipulating space and time with magic to create a new, miniature dimension within a pre-existing dimension with the purpose of short term storage. Items to which a holding spell has been cast are often referred to dimensional bags, d-bags, or bags of holding amongst other things.

The portals themselves, through which objects pass, are best described as three dimensional, non-visible spheres. Portals of Holding Spells may be attached to objects and can be moved from object to object. The Portal may be larger than the object it is attached to, 'clipping' through it in order to allow the entirety of a physical item to contain the portal, or in more advanced spells, conform to the interior of a container. In addition, if the object a holding spell's portal has been cast upon is destroyed, the holding spell will regurgitate its contents but remain in the same spatial location the object was at last relative to the largest high mass object (Earth).

It takes a considerable amount of power to create a holding spell, and a constant stream of energy to maintain it. However, the amount of energy necessary to maintain a holding spell's containment is significantly less than that needed to create the holding spell in the first place; the constant need of a source of magical power is one of the limiting factors of the holding spells, as a user's overexertion in using other types of magic may exhaust even the meager amount of power necessary to contain it's items.

In the event that the supply of power is cut off, the holding spell regurgitates all of its held items before collapsing. When altering the size of the portal, additional power is consumed, regardless of enlargement or shrinkage.

The capacity of any holding spell is proportional to the amount of power spent beyond the initial threshold of creation; the more power spent, the larger the capacity. After creation, the capacity of a holding spell cannot be adjusted.

The dimension inside the holding spell is completely devoid of matter, light and gravity. In addition, time is at a standstill in relativity to the user's dimension, rendering any objects placed within the holding spell in a state of stasis. More advanced versions of the typical holding spell may have time progress forward normally, or at an abnormally fast rate. Time may Not progress backwards inside a holding spell.