Distinguishes groups from questions and display text and indicates data type for questions
| Lvl | Code | Display | Definition |
| 1 | group | Group | An item with no direct answer but which has descendant items that are questions |
| 1 | display | Display | Text for display that will not capture an answer or have descendants |
| 1 | question | Question | An item that defines a specific answer to be captured (and may have descendant items) |
| 2 | boolean | Boolean | Question with a yes/no answer |
| 2 | decimal | Decimal | Question with is a real number answer |
| 2 | integer | Integer | Question with an integer answer |
| 2 | date | Date | Question with adate answer |
| 2 | dateTime | Date Time | Question with a date and time answer |
| 2 | instant | Instant | Question with a system timestamp answer |
| 2 | time | Time | Question with a time (hour/minute/second) answer independent of date. |
| 2 | string | String | Question with a short (few words to short sentence) free-text entry answer |
| 2 | text | Text | Question with a long (potentially multi-paragraph) free-text entry (still captured as a string) answer |
| 2 | url | Url | Question with a url (website, FTP site, etc.) answer |
| 2 | choice | Choice | Question with a Coding drawn from a list of options as an answer |
| 2 | open-choice | Open Choice | Answer is a Coding drawn from a list of options or a free-text entry captured as Coding.display |
| 2 | attachment | Attachment | Question with binary content such as a image, PDF, etc. as an answer |
| 2 | reference | Reference | Question with a reference to another resource (practitioner, organization, etc.) as an answer |
| 2 | quantity | Quantity | Question with a combination of a numeric value and unit, potentially with a comparator (<, >, etc.) as an answer. |