A structure is an organization of constituent features of a whole — an organization in virtue of which that whole can perform a function. Thus, Heidegger explains, structure is “read off” of a function (GA1  :417/BH 62).

One formally describes a structure by specifying the types of relationship that necessarily must obtain between types of elements in order for the whole to perform its function. Thus, everything that performs a certain function will possess those types of elements standing in that type of relation. If in a particular concrete case, a thing that is defined as performing a certain function lacks some of those elements, or if its elements don’t stand   in their proper relationship, then it is understood as a deficient case of instantiating the structure (but note that this means it is still understood in terms of possessing those elements in that relationship — in other words, it is understood as failing to fully instantiate the structure). [CHL  ]

structure

NT: Structure, Structural (Struktur  , struktural): of the question of being, 5-8 (§ 2), 14; of existence, 12, 44, et passim; of being-in-the-world, 41, 53, 58, 64, 66, et passim; of experience, 46; of Da-sein  , 54, 56, et passim; as-, 149, 151, 154, 158, 359-360; of care, 196, 259, 317, 323, 328, 331-332, 346, 350; end-structure, 244, 246; fore-structure, 151-153; of temporalization-structure, 332; of world, 366, 414; of truth, 216, 223, 226; structural moments, 5, 24, 41, 53, 63, 101, 117, 130-131, 140, 162, 176, 181, 209, 230, 232; totality (Strukturganzheit), 131, 182, 193, 209, 234, 334; whole, (Strukturganze), 65, 131, 180-184 (§ 39), 191-192, 231-233, 236, 252, 316-317, 323-325, 350. See also Constitution; Whole [BT]