The industry practice is to designate the partitioning as a series of three digits, indicating the number of hex digits used in each part: the Key Set ID, the TRSM ID, and the transaction counter. A common choice is '6-5-5', meaning that the first 6 hex digits of the KSN indicate the Key Set ID (i.e., which BDK is to be used), the next 5 are the TRSM ID (i.e. a device serial number within the range being initialized via a common BDK), and the last 5 are the transaction counter.