HL7
Standards for electronic interchange of clinical, financial, and administrative information among health care oriented computer systems; e.g. hospital information systems, clinical laboratory systems, enterprise systems, and pharmacy systems.
MS-HUG
Provides a foundation for 'plug and play compatibility between healthcare applications. Includes downloadable SDKs, and news releases.
NeoTool Development, LLC.
Offers tools and COM components to deal with HL7 messages. Also provides training, and consulting on HL7.