---
tags: USCDI v3
title: Machine Readable USCDI Cert Requirements
---

# Machine Readable USCDI Cert Requirements

US Core has a dual focus: ONC certification requirements and providing a base set of profiles for US implementers of FHIR. To ensure US Realm guides do not conflict with US Core profiles, US Realm created a requirement for variance requests. This process provides feedback to CGP and US Core IG developers, which helped recategorize elements as USCDI Certification Requirements elements. In addition to the Mandatory and Must Support elements that make up the base set of profiles for US implementers of FHIR, USCDI certified systems must support these additional elements using US Core Must Support criteria.

These additional USCDI Certification Requirements elements are defined in the narrative introductions to the corresponding profiles. Several implementers have requested they be machine-readableso that they are computationally discoverable. The following proposal outlines identifying these elements in the US Core profiles.

## Options for Identifying USCDI Certification Requirements elements in the US Core StructureDefinitions

### Option 1: Append BoilerPlate to Short Description and Definion

Append the text (e.g.,*USCDI*") to the element's `short description` and definition that flags all the elements that are ONC USCDI Requirements for certified systems. This text would be add to all current *Mandatory*, *Must Support*, and *USCDI Certification Requirements* elements

For example on the [US Core Patient Profile's](http://build.fhir.org/ig/HL7/US-Core/StructureDefinition-us-core-patient.html) Birthsex Extension:

~~~yaml
#...

-
id: 'Patient.extension:birthsex'
path: Patient.extension
sliceName: birthsex
#==== Appended Text ====
short: "Extension *USCDI*"#<<<Visible in tree views
definition: >-
blah blah blah....
**This element is an ONC USCDI Requirement**
#===================================
min: 0
max: '1'
type:
-
code: Extension
profile:
- 'http://hl7.org/fhir/us/core/StructureDefinition/us-core-birthsex'
mustSupport: false #<<<<< But not a US Core Must Support element
mapping:
-
identity: argonaut-dq-dstu2
map: Patient.extension
#....
~~~

#### Pros:

- Simple
- Human readable: will be exposed "all nice-n-pretty-like"
- kludgy-but machine readable
- No need for custom extension like in Option 2 or big bulky untested extension like in Option 3

#### Cons:

- Kludgy - This *should* be a FHIR Extension- see Options 2 and 3
- May be temporary solution and will be forced to replace it

### Option 2: Option 1 + ONC USCDI Requirements Flag Extension

A bespoke US Core Extension that flags all the elements that are ONC USCDI Requirements for certified systems. This extension would be add to all current *Mandatory*, *Must Support*, and *USCDI Certification Requirements* elements

For example on the [US Core Patient Profile's](http://build.fhir.org/ig/HL7/US-Core/StructureDefinition-us-core-patient.html) Birthsex Extension:

~~~yaml
#...

-
id: 'Patient.extension:birthsex'
#===ONC Certification Requirement Extension ====
extension:
- url: 'http://hl7.org/fhir/us/core/StructureDefinition/uscdi-requirements'
valueBoolean: true
#===================================
path: Patient.extension
sliceName: birthsex
#==== Appended Text ====
short: "Extension *USCDI*"#<<<Visible in tree views
definition: >-
blah blah blah....
**This element is an ONC USCDI Requirement**
#===================================
min: 0
max: '1'
type:
-
code: Extension
profile:
- 'http://hl7.org/fhir/us/core/StructureDefinition/us-core-birthsex'
mustSupport: false #<<<<< But not a US Core Must Support element
mapping:
-
identity: argonaut-dq-dstu2
map: Patient.extension
#....
~~~

#### Pros:

- Simple
- Machine readable

#### Cons:

- There is an FHIR R5 Extension for this - see Option 3
- May be temporary solution and will be forced to replace it
- The ig-publishing tooling will not expose the extension it "all nice-n-pretty-like" so need Option 1 too.

### Option 3: FHIR R5 [Obligation Extension](http://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-obligation.html) :grimacing:

Similarly, This complex extension could be added to all current Mandatory, Must Support, and USCDI Certification Requirements elements. We would also need to define an *ActorDefinition* and use an [obligation code](http://hl7.org/fhir/5.0.0-snapshot3/valueset-obligation.html).

1. define the ActorDefinition

~~~yaml
resourceType: ActorDefinition
id: us-core-certifier
url: 'http://hl7.org/fhir/us/core/ActorDefinition/us-core-certifier'
name: USCoreCertifier
title: US Core Certifier
status: active
date: '2023-02-27'
description: A health IT developer certifying to ONC’s USCDI certification criterion
type: system
~~~

2. For example on the [US Core Patient Profile's](http://build.fhir.org/ig/HL7/US-Core/StructureDefinition-us-core-patient.html) Birthsex Extension:

~~~yaml
#...

-
id: 'Patient.extension:birthsex'
#======= Obligation Extension =======
extension:
- url: 'http://hl7.org/fhir/StructureDefinition/obligation'
extension:
- url: 'code'
valueCoding: SHALL:can-send
extension:
- url: 'actor'
valueCanonical: http://hl7.org/fhir/us/core/ActorDefinition/us-core-certifier
extension:
- url: 'documentation'
valueMarkdown: A health IT developer certifying to ONC’s USCDI certification criterion, must support this element as defined on the Confomance page.
#===================================
path: Patient.extension
sliceName: birthsex
min: 0
max: '1'
type:
-
code: Extension
profile:
- 'http://hl7.org/fhir/us/core/StructureDefinition/us-core-birthsex'
mustSupport: false #<<<<< But not a US Core Must Support element
mapping:
-
identity: argonaut-dq-dstu2
map: Patient.extension
#....
~~~

#### Pros:

- Part of FHIR R5 Extension
- Machine readable
- Expectation that the ig-publishing tooling will expose this "all nice-n-pretty-like"

#### Cons:

- Part of FHIR R5 Extension - Brand new and untested (no budget for US Core to pilot it)
- Complex
- Required Codes don't align with US Core Must Support Rules