This page is part of the FHIR Specification (v5.0.0-ballot: R5 Ballot - see ballot notes). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions

FHIR Infrastructure Work Group

Maturity Level: N/A

Standards Status: Informative

2.1.13 Transforms between R4 and R5

Note to Balloters: The R4 / R5 version comparison information is updated prior to publication of the final copy of R5. At this point in time (ballot) it has not been updated. Ballot comments concerning this information are welcome to identify issues, but will not be counted as negative.

In addition to a list of all differences between R4 and R5, this specification also provides transforms between R4 and R5 for most resources that were in R5. These transforms are expressed using the FHIR Mapping Language, and both serve as formal documentation of the relationship between the resource structures in R4 and R5, and can also be used to convert between the formats automatically.

The following table summarizes the state of the R5:R5 maps for each resource type.

Note the following:

• Transforms are tested using the following method:
  1. For each example resource in the R4 release of the FHIR specification that has a transform to R5
  2. apply the transform to R5
  3. validate against the R5 specification
  4. apply the reverse transform back to R4
  5. compare the outcome with the original resource - ideally, it should be identical
• All transforms should execute - that is, they should be able to take any R4 resource, represent the content in R5, and then generate an R4 representation for the same content. Note, though, that in a few cases, the differences between R4 and R5 designs are so significant that not all examples can be successfully transformed at all.
• For some resources, the differences in design between R4 and R5 are sufficiently great that the R4 examples cannot reproduce the same output after conversion to R5 and then back to R4. For example, the R5 resource may have a different set of status codes with imperfect maps
• For some resources, the information available in the R4 examples is not enough to generate valid R5 resources, and so the resources generate R5 validation errors. (e.g. R4 resources missing an element that is required in R5)
• The transform scripts are only tested to the degree that R4 provided example data
• For all these reasons, the maps provided in the specification are not authoritative; they are provided to help implementers who need to convert between the R2 and R4 format, but additional revision may be required in an implementation specific context
• The maps are subject to ongoing maintenance using the FHIR NPM Package "fhir.versions.r3r4" which is maintained on GitHub . See also FHIR Wiki for other ongoing work to support R4/R5 transformations