Before we start, there are few things that need explanation!
For any exchange and subsequent interpretation of health data, addressing interoperability is a must. Interoperability can be broadly classified in two aspects that need to be solved.
The aim of the reference stack, is to solve the Syntactic interoperability, thus allowing a machine readable format for systems that consume the data. We use HL7 FHIR as data formats to solve the syntactic interoperability.
Semantic interoperability can be achieved by adopting a common standard; typically in health domain, by means of adopting common terminology / coding standards. Examples of such standards are SNOMED-CT, ICD10, LOINC etc. India already has member country license and National Resource Centre for EHR Standards (NRCeS) NRC maintains so. Anyone in India can get the license free of cost from NRCeS, by registering as MLDS. Please visit here for more information on how to get the license. We understand that adoption and mapping of Clinical terminologies can be a arduous process, and hence the documentation reflects the simplistic approach anyone can take to send machine readable standard format data. At the same time, if you would want to send the data using standard clinical terminologies mapping - you are much welcome and encouraged. We will continue to embrace/interpret standard terminologies and hope to evolve progressively, as adoption and implementation of EHR/EMR, points-of-care systems, end user systems happen. Please refer to relevant standards define by authorities relevant to you.
For details on the Data formats in the reference stack, please refer to the WIKI.