| Code | Display | Definition | 
| MORN  | 
Morning | 
Event occurs during the morning. The exact time is unspecified and established by institution convention or patient interpretation. | 
| MORN.early  | 
Early Morning | 
Event occurs during the early morning. The exact time is unspecified and established by institution convention or patient interpretation. | 
| MORN.late  | 
Late Morning | 
Event occurs during the late morning. The exact time is unspecified and established by institution convention or patient interpretation. | 
| NOON  | 
Noon | 
Event occurs around 12:00pm. The exact time is unspecified and established by institution convention or patient interpretation. | 
| AFT  | 
Afternoon | 
Event occurs during the afternoon. The exact time is unspecified and established by institution convention or patient interpretation. | 
| AFT.early  | 
Early Afternoon | 
Event occurs during the early afternoon. The exact time is unspecified and established by institution convention or patient interpretation. | 
| AFT.late  | 
Late Afternoon | 
Event occurs during the late afternoon. The exact time is unspecified and established by institution convention or patient interpretation. | 
| EVE  | 
Evening | 
Event occurs during the evening. The exact time is unspecified and established by institution convention or patient interpretation. | 
| EVE.early  | 
Early Evening | 
Event occurs during the early evening. The exact time is unspecified and established by institution convention or patient interpretation. | 
| EVE.late  | 
Late Evening | 
Event occurs during the late evening. The exact time is unspecified and established by institution convention or patient interpretation. | 
| NIGHT  | 
Night | 
Event occurs during the night. The exact time is unspecified and established by institution convention or patient interpretation. | 
| PHS  | 
After Sleep | 
Event occurs [offset] after subject goes to sleep. The exact time is unspecified and established by institution convention or patient interpretation. | 
| IMD  | 
Immediate | 
Event occurs a single time (with no repetitions) as soon as possible after the scheduled or actual start of the overall event. |