| Inbound Relationships | Type | Active | Source | Characteristic | Refinability | Group | 
| Mechanical dead space, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Lung volume, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Regional tidal volume, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Airway closing volume, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Thoracic gas volume, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Standardized volume history, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Maximum breathing capacity, function | Is a | False | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Alveolar dead space, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Alveolar gas volume, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Forced expiratory vital capacity, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Diffusion capacity of lung, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Stratified dead space, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Forced expiratory volume, function (observable entity) | Is a | False | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Pulmonary dead space, function | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Vital capacity, function (observable entity) | Is a | False | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Ability to perform spirometry | Is a | True | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  | 
| Spirometric lung age | Is a | False | Lung volume AND/OR capacity, function | Inferred relationship | Existential restriction modifier |  |