Question: In a USIM's EFEXT8 file for MMS Notification extensions, what does the first byte of the 'Extension data' field typically represent?
Option 1: The total size of the EFEXT8 file in bytes
Option 2: The record type for MMS notifications
Option 3: The identifier for the next extension record in the chain
Option 4: The number of bytes in the remainder of the MMS notification in this record
Explanation: According to USIM application specifications, the first byte of the 'Extension data' field in EFEXT8 indicates the length (in bytes) of the remaining MMS notification data within that record, enabling efficient parsing and processing of notification extensions.