I am researching about electronic health records (EHR). OpenEHR seems to be quite extended and appreciated in this field, as it is widely adopted. However, I fail to find how it
Records are compiled and transmitted in XML to other vendors or organizations. HL7 is used for sending messages such as lab orders to/from lab vendors with specific OBR and OBX.
I'm not sure what you are looking to do with your research - if you're building your own app/site, then I would suggest blue button plus. It is an initiative by the ONC and the js will parse most CCDA (XML document with patient info from EHR) documents. Look over the library on GitHub - https://github.com/blue-button/bluebutton.js
Most importantly, research the background (HITECH Act) and know the challenges (EHR interoperability). Go to HHS.gov and look over the information there. Also, you're going to need someone who knows medical terminology and codes (ICDs, CPTs, SNOMED, etc.) as well as a clinical advisor because you could have all the data in the world, but if you don't display it in a proper or meaningful way, it's essentially useless.