| Description: The value indicates what detector of the GRS instrument measured the observation. | 
| Namespace Id: mess | Steward: ppi | Class Name: MESSENGER | Type: ASCII_Short_String_Collapsed | 
| Minimum Value: None | Maximum Value: None | Minimum Characters: 1 | Maximum Characters: 255 | 
| Unit of Measure Type: None | Default Unit Id: None | Attribute Concept: None | Conceptual Domain: SHORT_STRING | 
| Status: Active | Nillable: false | Pattern: None | 
| Permissible Value(s) | Value | Value Meaning | 
|  | acs | Measurement from the GRS anti-coincidence shield. | 
|  | hpge | Measurement from the high purity Germanium (HPGe) detector. | 
|  | microphonics | Measurement from the microphoncis detector. | 
|  | shield | Measurement from the GRS shield detector |