FHIR Packages are now documented directly in the FHIR specification: http://hl7.org/fhir/packages.html
NOTE: This page is under the management of FHIR Infrastructure. All substantive changes to this specification require formal review and approval by the FHIR-I Working Group.
A FHIR package groups a coherent collection of conformance resources, like StructureDefinitions and ValueSets into an easily distributed NPM package. FHIR packages use a subset of the features used by npm packages.