This page is part of the FHIR Specification (v0.0.82: DSTU 1). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions

1.5 DSTU Considerations

FHIR is being published as a Draft Standard for Trial Use (DSTU). The specification that is the standard undergoing trial use includes all the content with a URL starting with "http://hl7.org/fhir/DSTU1" , with the following exceptions:

This content which is not part of the DSTU are updated on a regular basis. Changes to the specification itself are subject to formal review, following HL7 DSTU processes. Changes are announced on the FHIR email list.

Note that this specification includes many examples. While every effort has been made to ensure that the examples are fully conformant to the specification, if the examples disagree with the specification, the specification is considered correct and normative, and not the examples. This same rule applies to the reference implementations.

Attention Implementers, Regulators, standards development organizations and other users (and potential users) of this specification

The DSTU label has been used with prior HL7 specifications with varying intentions. As well, those making use of FHIR may not be familiar with HL7 standards processes. For this reason, the FHIR Management Group is providing the following guidance for the users of the FHIR specification to make clear HL7's intentions.

The FHIR specification is "draft". It has been subject to significant review through ballot and other HL7 processes and many aspects of it have been implemented and subjected to interoperability testing through Connectathons and early adoption. However, the degree of testing has varied. Some resources have been well tested in a variety of environments. Others have received relatively little real-world exercise. In general, the infrastructure should be considered to be more stable than the resources themselves. In some cases, there are issues on which input is specifically requested during the DSTU period (see the Outstanding Issue List, and known issues will arise after publication (refer to the FHIR Change Request tracker for details.) Guidance from early implementation will help address these areas.

Regardless of the degree of prior implementation, all aspects of the FHIR specification are potentially subject to change. These changes may be minor (clarifications of definitions, etc.) or major (refactoring of resources, changes to serialization rules, eliminating or adding data types, etc.) There is no commitment to backward or forward compatibility during the DSTU process. Changes will not be made without cause, however the interests of long-term implementability will generally trump the impact on early adopters when determining what changes should be made.

This specification has been promoted to DSTU because it is felt that the specification, as is, is implementable and that more value can be gleaned from implementer experience than from subsequent review as part of the ballot process. Implementers who are willing to accept the risk of change (perhaps for the benefit of early implementation experience, first mover advantage and the ability to leverage FHIR's intrinsic benefits) are encouraged to implement FHIR in real-world systems. However, those implementers should be aware that local adaptations may be necessary to meet real-world requirements. Furthermore, such implementers should architect their solutions to be tolerant of changes to the specification and, where necessary, to manage interoperability with systems that may be using different versions of the specification or different local adaptations.

It is the HL7's expectation that at least two DSTU releases (roughly a year apart) will be published prior to balloting the specification as a Normative specification. Once the specification becomes Normative, all stated commitments to backwards compatibility will come into play. The normative specification will include all infrastructure components of FHIR as well as those resources that have been implemented in a sufficient number of diverse environments. Some resources may be left as "informative" within the normative release until such time as sufficient implementation experience has been gained. Backwards compatibility rules will not be binding on these informative resources.

During the DSTU period, requests for change may be submitted using the HL7 gForge tracker which can be found here. Where possible, updates to the "development" version of the specification will be made in a timely fashion. A list of these proposed changes will be published as a continuously updated supplement to the official DSTU publication. Implementers should be aware that the changes are not considered "official" until such time as they are balloted and approved as part of a subsequent DSTU or Normative publication. Change requests might be fixes to allow implementation, clarifications or enhancements. In addition, HL7 will be developing and introducing additional resources and profiles as part of the FHIR specification.

SDOs and regulatory bodies that are interested in making use of the FHIR specification should feel free to do so, but should consider and plan for the possibility that the specification will evolve and change prior to becoming normative.

A key objective of the DSTU process is gaining feedback from implementers making use of the specification. As well, the HL7 has a need to monitor which portions of FHIR are being implemented in what sorts of environments so as to make an informed decision on when the specification is ready to proceed to Normative status. For this reason, all FHIR implementers are asked to complete a short survey which can be found here.

This survey will capture contact and other information that will allow the FMG to perform appropriate monitoring of FHIR DSTU usage. Survey information will be kept confidential unless the participant authorizes inclusion of their project in an HL7-maintained wiki page of early implementers. Confidential submissions will be reported in aggregate only.

While implementation of the first DSTU release is occurring, development will be progressing on the next DSTU release. This second release will include additional resources, profiles and quality enhancements over the current release. It will also incorporate fixes for issues raised with the FHIR change tracker. It may be useful for implementers of the DSTU to browse the development release to get a sense of what changes are likely coming and perhaps to find more robust definitions and guidance than are available in the first release. The FHIR development release can be found at hl7.org/fhir-develop.

Thank you for participating with us in this process. We look forward to your feedback and hope you enjoy making use of the specification.

The FHIR Management Group (FMG), on behalf of HL7

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