The alphanumeric string "F87B1364" likely serves as a unique identifier or a value.
how to find file info in not-first rar file? · Issue #56 · markokr/rarfile F87B1364.rar
These are mathematical values calculated from the file's contents to verify its integrity. If the file is altered by even one bit, the checksum will change. The alphanumeric string "F87B1364" likely serves as a