Specifications

Intel
®
64 and IA-32 Architectures Software Developer’s Manual Documentation Changes 10
Documentation Changes
3.1.1.4 64-bit Mode Column in the Instruction Summary Table
The “64-bit Mode” column indicates whether the opcode sequence is supported in 64-bit
mode. The column uses the following notation:
Valid — Supported.
Invalid — Not supported.
N.E. — Indicates an instruction syntax is not encodable in 64-bit mode (it may
represent part of a sequence of valid instructions in other modes).
N.P. — Indicates the REX prefix does not affect the legacy instruction in 64-bit
mode.
N.I. — Indicates the opcode is treated as a new instruction in 64-bit mode.
N.S. — Indicates an instruction syntax that requires an address override prefix in
64-bit mode and is not supported. Using an address override prefix in 64-bit mode
may result in model-specific execution behavior.
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