What constitutes legal possession for items that cannot be moved or transferred?

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Possession for items that cannot be moved or transferred is established by vacating the space (takhliyah) between the item and the buyer, without any barrier remaining. This principle is also applied regarding pledges, where possession of an immovable pledged item is established by the pledgor leaving the object unobstructed between himself and the pledgee. Since possession is used generally in the Sacred Law (Shari'ah), recourse must be made to custom ('urf), as seen with 'ihraz' (marking boundaries) and 'tafarruq' (separation/dispersal).