Consider x86 16 bit mode instruction:

$ echo 66 EA 66 55 44 33 22 11 | xxd -p -r | ndisasm -b16 -
00000000  66EA665544332211  jmp dword 0x1122:0x33445566

I thought 16 bit code jumps work by combining two 16 bit parts, while 32 bit code just uses 32 bit offset without segment part. What's the meaning of having both segment offset and 32 bit offset?