==== 4.2.1 The AID Format ====

This section presents a minimal description of the AID data format used in Java Card technology. For complete details, refer to ISO 7816-5, AID Registration Category `D' format. 

The AID format used by the Java Card platform is an array of bytes that can be interpreted as two distinct pieces, as shown in [[4._Binary_Representation| TABLE 4-1]]. The first piece is a 5-byte value known as a RID (resource identifier). The second piece is a variable length value known as a PIX (proprietary identifier extension). A PIX can be from 0 to 11 bytes in length. Thus an AID can be from 5 to 16 bytes in total length. 

 

RID (5 bytes) 

PIX (0-11 bytes)       

ISO controls the assignment of RIDs to companies, with each company obtaining its own unique RID from the ISO. Companies manage assignment of PIXs for AIDs using their own RIDs.