STANAG 4626
STANAG 4626 is a NATO Standardization Agreement which defines a set of Open Architecture Standards for Avionics Architecture, particularly in the field of Integrated Modular Avionics. The purpose of this standard is to establish uniform requirements for the architecture for Integrated Modular Avionics (IMA) systems as defined by the ASAAC program. A reference implementation is on SourceForge under an Apache license.
STANAG 4626 is a NATO Standardization Agreement which defines a set of Open Architecture Standards for Avionics Architecture, particularly in the field of Integrated Modular Avionics. The purpose of this standard is to establish uniform requirements for the architecture for Integrated Modular Avionics (IMA) systems as defined by the ASAAC program. A reference implementation is on SourceForge under an Apache license.

History
This STANAG was proposed by the UK Ministry of Defence, and originated from the ASAAC effort. As for ASAAC, many major European Avionics companies  participate in its definition, such as:

BAE Systems
GE Aviation Systems (formerly Smiths Aerospace)
Dassault Aviation
Thales Group
Airbus (formerly EADS)
ESG Elektroniksystem- und Logistik-GmbH
GMV Innovating Solutions

See also
ASAAC
Integrated Modular Avionics
ARINC 653

External links
STANAG 4626 part I on everyspec.com
Open Source OS adaption layer for STANAG 4626 on sourceforge.net