A technical standard is an established norm or requirement in regard to technical systems. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes and practices. In contrast, a custom, convention, company product, corporate standard, etc. that becomes generally accepted and dominant is often called a de facto standard. Wikipedia

List of IOC country codes
Country code
ISO 3166-1 - defines codes for the names of countries, dependent territories, and special areas of geographical interest
ISO 3166-2 - defines codes for identifying the principal subdivisions (e.g., provinces or states) of all countries coded in ISO 3166-1
ISO 3166-3 - defines codes for country names which have been deleted from ISO 3166-1

RUS - Russia
SUHH - Soviet Union