Code systems

Code systems define the valid values for coded fields in Blue Button responses. When you see a coding object in a response, the system URI tells you which code system to look up.

What is a code system?

In FHIR, a code system is a defined set of codes with meanings. For example, the eob-type code system defines codes like CARRIER, INPATIENT, and PDE that identify claim types. When you see:

{
  "system": "https://bluebutton.cms.gov/fhir/CodeSystem/EOB-TYPE",
  "code": "CARRIER"
}

…you know this is a carrier (physician/supplier) claim.

How coding systems work

FHIR uses coding systems to represent standardized values. A coded value has three parts:

{
  "coding": [
    {
      "system": "https://bluebutton.cms.gov/resources/codesystem/eob-type",
      "code": "CARRIER",
      "display": "Carrier (professional) claim"
    }
  ]
}

• system A URI identifying which coding system the code belongs to
• code The coded value
• display Human-readable description

Blue Button uses coding systems from several sources:

For a complete listing: Blue Button Code System Listing

Industry-standard code systems

The Blue Button API supplies codified data using several terminology and coding systems:

Using Code Systems with the Blue Button API

Find details about coding systems in the Blue Button Code System Listing.

The Blue Button API also provides data in FHIR Extensions . FHIR extensions are custom data elements that are not found in the FHIR standard. Check the data dictionary for further details.