The RID is part of an Application Identifier (AID), which is structured according to ISO/IEC 7816-5 and consists of two parts:
- The RID, unique to an application provider and assigned according to ISO/IEC 7816-5.
- An optional field assigned by the application provider known as a Proprietary Application Identifier Extension (PIX), used to identify different applications or products.
- Registration application provider identifier (International RID, five bytes set to "AX")
- Proprietary application identifier extension (PIX, up to eleven bytes - fee coding)