This enumeration represents capability control messages.
Values:
| IG_TW_MSG_GET | Get one or more values. |
| IG_TW_MSG_GETCURRENT | Get current value. |
| IG_TW_MSG_GETDEFAULT | Get default (e.g., power up) value. |
| IG_TW_MSG_GETFIRST | Get first value. |
| IG_TW_MSG_GETNEXT | Get next value. |
| IG_TW_MSG_QUERYSUPPORT | Query capability support. |
| IG_TW_MSG_RESET | Set current value to default value. |
| IG_TW_MSG_SET | Set one or more values. |