'Why doesn't instruction opcode 0xBB exists? [duplicate]

I'm currently writing a virtual machine and I've realised that 0xBB is not a valid instruction when it should be.

I tried using shellstorm with the assembly instruction of:

mov EBX, 0xffffffff

which gave me bb ff ff ff ff. But after looking in 4 different x86 instruction listing manuals I could find, the 0xBB opcode seems to not exist or it's taken by a different instruction. I thought it was just shellstorm being wrong so I tried a different online assembler using defuse, but it gave me the same result. Can anybody tell me why is this the case?

EDIT:

I misunderstood the purpose of the + symbol next to some opcodes, so 0xB8+ is the actual instruction I was finding for.

assemblyx86opcode


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