IOD Usage Constants
The following constants are used to indicate the usage of Information Object Definitions.
| Code constant | Code value and meaning | 
| DICOM_IOD_USAGE_M | [0x00] Mandatory IOD | 
| DICOM_IOD_USAGE_C | [0x01] Conditional IOD | 
| DICOM_IOD_USAGE_U | [0x02] Optional IOD | 
| DICOM_IOD_USAGE_1 | [0x03] Mandatory IOD - type 1 | 
| DICOM_IOD_USAGE_1C | [0x04] Conditional IOD - type 1 | 
| DICOM_IOD_USAGE_2 | [0x05] Mandatory IOD - type 2 | 
| DICOM_IOD_USAGE_2C | [0x06] Conditional IOD - type 2 | 
| DICOM_IOD_USAGE_3 | [0x07] Optional IOD - type 3 |