| Microsoft DirectX 9.0 |
Specifies the hierarchy alpha on a Digital Video Broadcasting-Terrestrial (DVB-T) system.
| Constants | Value | Description |
| BDA_HALPHA_NOT_SET | -1 | The hierarchy alpha is not set. |
| BDA_HALPHA_NOT_DEFINED | 0 | The hierarchy alpha is not defined. |
| BDA_HALPHA_1 | 1 | The hierarchy alpha is 1. |
| BDA_HALPHA_2 | 2 | The hierarchy alpha is 2. |
| BDA_HALPHA_4 | 3 | The hierarchy alpha is 4. |
| BDA_HALPHA_MAX | 4 | The hierarchy alpha is the maximum. |