• MAGIC number

• Class
  • 0 = None (Invalid)
  • 1 = 32 Bit Objects
  • 2 = 64 Bit Objects
• Data
  • 0 = None (Invalid)
  • 1 = Least Significant Byte First (Little endian)
  • 2 = Most Significant Byte First (Big endian)
• Version
  • Always 1
• OS ABI
  • 0 = None/System V(=Unix V) (very Common)
  • 1 = HP-UX
  • 2 = NetBSD
  • 3 = Linux
  • ...
• ABI version: Almost not used
• Padding: 나머지 7개 비트