> ## Documentation Index
> Fetch the complete documentation index at: https://medlogprotocol.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Health data elements

> Reusing USCDI data classes and FHIR resources to anchor MedLog records to standardized clinical entities.

## USCDI

[USCDI](https://isp.healthit.gov/united-states-core-data-interoperability-uscdi) defines data classes
and elements for interoperable health information exchange. These elements can be reused within MedLog
records.

| MedLog field | Related USCDI concepts |
| - | - |
| [User identity](/specification/user-identity) | [Care Team Members](https://isp.healthit.gov/uscdi-data-class/care-team-members) and [Facility Information](https://isp.healthit.gov/uscdi-data-class/facility-information) |
| [Target identity](/specification/target-identity) | [Patient](https://isp.healthit.gov/uscdi-data-class/patient-demographicsinformation) and [Encounter](https://isp.healthit.gov/uscdi-data-class/encounter-information) identifiers |
| [Inputs](/specification/inputs) | [Laboratory](https://isp.healthit.gov/uscdi-data-class/laboratory), [Vital Signs](https://isp.healthit.gov/uscdi-data-class/vital-signs), [Medications](https://isp.healthit.gov/uscdi-data-class/medications), [Clinical Notes](https://isp.healthit.gov/uscdi-data-class/clinical-notes), and [Diagnostic Imaging](https://isp.healthit.gov/uscdi-data-class/diagnostic-imaging) |
| [Outcomes](/specification/outcomes) | [Adverse Events](https://isp.healthit.gov/uscdi-data/adverse-event) |

## FHIR

[Fast Healthcare Interoperability Resources (FHIR)](https://hl7.org/fhir/) data formats and elements can
also anchor MedLog entries to standardized clinical entities.

<AccordionGroup>
  <Accordion title="Header" icon="fingerprint">
    [`AuditEvent.occurredPeriod`](https://hl7.org/fhir/R5/auditevent.html) can represent the execution
    interval and
    [`AuditEvent.recorded`](https://hl7.org/fhir/R5/auditevent-definitions.html#AuditEvent.recorded) can
    record when the MedLog record was logged.
  </Accordion>

  <Accordion title="User identity" icon="gears">
    [`AuditEvent.agent`](https://hl7.org/fhir/R5/auditevent-definitions.html#AuditEvent.agent) can
    identify the immediate calling service, with the account identifier recorded in
    [`AuditEvent.agent.who.identifier`](https://hl7.org/fhir/R5/auditevent-definitions.html#AuditEvent.agent.who)
    and security role in
    [`AuditEvent.agent.role`](https://hl7.org/fhir/R5/auditevent-definitions.html#AuditEvent.agent.role).
    When possible, references to [`Practitioner`](https://hl7.org/fhir/R5/practitioner.html) or
    [`PractitionerRole`](https://hl7.org/fhir/R5/practitionerrole.html) can link the account to the human
    user and clinical role context.
  </Accordion>

  <Accordion title="Target identity" icon="crosshairs">
    Target identity can reference an existing [`Patient`](https://hl7.org/fhir/R5/patient.html),
    [`Appointment`](https://hl7.org/fhir/R5/appointment.html), or other appropriate resource, with
    [`Encounter`](https://hl7.org/fhir/R5/encounter.html) providing encounter context where applicable.
  </Accordion>

  <Accordion title="Model instance" icon="microchip">
    A software model can be represented by a [`Device`](https://hl7.org/fhir/R5/device.html) containing
    its identifier and software version.
  </Accordion>

  <Accordion title="Inputs and outputs" icon="right-left">
    Inputs can reference [`Observation`](https://hl7.org/fhir/R5/observation.html) or
    [`DocumentReference`](https://hl7.org/fhir/R5/documentreference.html), for example, while outputs can
    use FHIR resources appropriate to their clinical meaning, such as
    [`RiskAssessment`](https://hl7.org/fhir/R5/riskassessment.html) for a risk prediction or
    `DocumentReference` for a generated document.
  </Accordion>

  <Accordion title="User feedback" icon="comment-check">
    User feedback collected through a defined questionnaire can use
    [`QuestionnaireResponse`](https://hl7.org/fhir/R5/questionnaireresponse.html).
  </Accordion>
</AccordionGroup>

<Note>
  These are only illustrative examples of the many possible FHIR fields which could be used to represent
  or reference information in MedLog records. The
  [field mapping explorer](/interoperability/field-mapping) shows the full set side by side with USCDI
  and OpenTelemetry.
</Note>