The map of FHIR

A large specification. Where do you start?

The FHIR specification is large. Where do you start? You start with the map. The home page lays FHIR out in five levels, from the foundation up to reasoning.

From foundation to reasoning

Level one is the foundation: the basic framework on which the specification is built. Level two supports implementation and binding to external specifications: implementer support, security and privacy, conformance, terminology and exchange. Level three links to real world concepts, such as patients, practitioners and organizations. Level four is record keeping and data exchange for the healthcare process: clinical, diagnostics, medications, workflow and financial. And level five provides the ability to reason about the healthcare process.

• Level 5: reasoning · The ability to reason about the healthcare process. · bolt
• Level 4: the care process · Record keeping and data exchange. · file
• Level 3: the real world · Patients, practitioners, organizations and more. · building
• Level 2: support · Security, terminology, exchange. · gear
• Level 1: foundation · The basic framework everything is built on. · layers

The levels, as the specification shows them

This is the real page. On the specification's home page, level one is the foundation: base documentation, the XML and JSON formats, datatypes, and extensions. Level two has five modules: implementer support, security and privacy, conformance, terminology, and exchange. The rest of the levels continue below on the page.

• 1 · 0.012 · 0.105 · 0.973 · 0.18
• 2 · 0.012 · 0.395 · 0.973 · 0.595
• 1 · Level 1: Foundation · Formats, datatypes, extensions.
• 2 · Level 2: five modules · Support, security, conformance, terminology, exchange.

Where the healthcare process lives

Level four is where most clinical and business content sits. The clinical module covers items such as allergies, problems, procedures and care plans. Diagnostics covers observations, reports, specimens and imaging studies. Medications covers medication, requests, dispensing, administration and immunization. And workflow and financial cover items such as tasks, appointments, referrals, claims and coverage.

• Clinical · navy
• Diagnostics · amber
• Medications · slate
• Workflow and financial · deep

A reading order for the specification

The specification's own overview suggests where to start. First, read the list of resources, to get a sense of what exists. Then look at the patient resource definition, to see what a resource definition looks like. Then read the background pages on how resources are defined, how they refer to each other, the formats, and extensibility. And if you come from HL7 version two, version three or C D A, read how FHIR relates to them.

• First · The resource list · See what resources exist. · file
• Second · The Patient resource · See what a definition looks like. · person
• Third · The background pages · Definitions, references, formats, extensibility. · text
• If you know HL7 · How FHIR relates · For readers of V2, v3 or CDA. · link

From care to plumbing

Resources have a wide range of uses. At one end is clinical content, such as care plans and diagnostic reports. At the other is pure infrastructure, such as the message header and the capability statement. They share common technical characteristics, but they are used in different ways. And you do not have to use REST to make use of resources.

Check yourself

Pause and think. How many levels does the FHIR home page use to lay out the specification? The answer: five, from the foundation up to reasoning.

• Five
• Three
• Seven
• Twelve

Keep these in mind

FHIR is laid out in five levels, with the foundation at the bottom and reasoning at the top. Level four holds the healthcare process modules. And to start reading, take the resource list, then the patient resource, then the background pages.

• FHIR is laid out in five levels
• Foundation at the bottom, reasoning at the top
• Level four holds the healthcare process modules
• Read the resource list, then Patient, then the background