Introduction

Fast Healthcare Interoperability Resources (FHIR) is a standard describing data formats and elements and an application programming interface for exchanging electronic health records. The standard was created by the Health Level Seven International healthcare standards organization. Data must be packaged according to the FHIR guidelines to ensure a smooth transfer. The Nation Resource Centre for EHR Standards in India has given implementation guidelines (https://www.nrces.in/ndhm/fhir/r4/index.html) which are in sync with NDHM. The Health Information types supported by NDHM currently are Prescription Record, Diagnostic Report, OP Consultation Record, Discharge Summary Record and Immunization Record.

Each of the Health Information Types has some mandatory, must support and fixed value elements that need to be implemented in order to generate a valid JSON String which can then be used for Data Transfer after it has been encrypted. The convention followed by FHIR for the Health Information Types are:

• Cardinality (a..b) indicates the minimum (a) and maximum (b) number of times an element can occur in the instance. So the elements with cardinality (1..1) or (1..*) indicate Mandatory Elements.

• Must Support Elements are flagged by a Red Box with an 'S' inside it.

• Fixed Value Elements are those whose value cannot be changed and need to remain constant. For example: " Composition.type.coding.system " has a fixed value " http://snomed.info/sct ".

• Each instance might have nested instances in which case all the nested instances will follow the above convention.