4. USABILITY OF OSAThe key concept

4. USABILITY OF OSAThe key concept is 'conformance to the standard,' and the language used in the POSIX standards [9] works well to capture these concepts. Vendors provide a 'conforming implementation' when they implement all required parts of the standard. (Some vendors have claimed 'we comply with this standard' when they implement a subset of the features of POSIX; the term 'compliance' has no formal definition and means whatever the vendor wants it to mean.) The applications developer produces 'conforming applications' by using only the features of the standard, and adapting to any customizations permitted by the standard. The UAV community has had a large degree of success in moving to STANAG 4856. The next phase of the migration to an OSA is a work in progress.Determining a 'conforming implementation', i.e., buying a system that meets the requirements of the standard, usually requires a combination of testing and of vendor documentation. Determining a 'conforming application' is a harder task, because testing does not necessarily reveal if the application uses only the facilities of the standard. An implementation may well provide extensions to the standard, including behavior within the standard interface that does things not guaranteed by the standard. As part of the Business Strategy of FACE, the Conformance Subcommittee has developed the FACE Conformance process. And the FACE Technical Committee has defined a Conformance Verification Matrix (CVM) which identifies the specific requirements, methods of verification, and associated verification evidence. OMS defines a Compliance Verification Cross Reference Matrix (VCRM) which contains all of the OMS requirements and the associated verification requirements and acceptance criteria.A standard supports its user community when the specification is sufficient to meet the user needs, complete with respect to all parameter values, behaviors, etc., and has a well-defined conformance approach. For FACE, the FACE Trademark Licensor issues the FACE Conformance Certification Trademark for Certified Units of Conformance and Certified Unit of Conformance Packages thus allowing a third party to easily determine if a component is FACE conformant.The real test of all of these OSA efforts will occur when multiple suppliers offer similar capabilities and these modules can be easily integrated into their target systems.