The entity must be uprooted from, and set down on, a space of four handbreadths by four handbreadths, in order for one to be liable: Eruvin 9a, 76b-77a, 85b, 87a-b, 99a, 101b
Setting an entity down on, or removing an entity from, a place which is significant in that this is where the person intended for the item to be, but is less than sixteen square handbreadths: Eruvin 99a
Picking up an item - akirah
An act of Uprooting which in removing the item makes the place it came from into a Private Property: Shabbat 99b
Setting down an item - hanachah
Considering one's hand as a location of four-by-four cubits, so that holding it in one's hand is an act of hanachah: Ketuvot 31b
An act of Setting Down which places down an item, making the place it is set down on a Private Property: Shabbat 99b
Above, where an item is placed on top of the subject of the Setting Down: Shabbat 99b
Considering an item which is in mid-air, below 3 Tefach [Hand-Breadths], to have landed: Shabbat 100a-b; Eruvin 98b
