| region_dTReturn the current region (valid values: 1,2,3,4,5) in IF97, given density and temperature |  | 
| d | Type: Density (kg/m³) Description: Density | 
|---|---|
| T | Type: Temperature (K) Description: Temperature (K) | 
| phase | Default Value: 0 Type: Integer Description: Phase: 2 for two-phase, 1 for one phase, 0 if not known | 
| mode | Default Value: 0 Type: Integer Description: Mode: 0 means check, otherwise assume region=mode | 
| region | Type: Integer Description: (valid values: 1,2,3,4,5) in IF97 | 
|---|