Hello thomas,
ffehr is using XUL of mozilla and run's preferably under the xulrunner engine. Part of the goal is to have it under a small USB device and need not have any network access. Ffehr should be able to serve in areas where net access is not reliable or non-existent.
Upon googling for HL7 specs I have stumbled upon openEHR, which I find to have it's specs open for the public to download. However, my expertise is not so much in this area but I am doing my best to learn it. The current solution that I see is to make a good standardization of XML in ffehr and provide a plugin for XSLT export to HL7 and/or openEHR.
Of course, it's also interesting to parse openEHR and HL7 via XSLT and render a xul page.
Sincerely,
NBJayme