A command that is available in one Microsoft operating system is not necessarily available in another. Microsoft regularly adds and removes commands from one version of Windows to another, usually to remove or add certain features.
40 Windows Commands You MUST Know (in 10 Minutes)
This is a complete list of assignments and their availability.
[1] This command is not available in 64-bit versions of this operating system.
[2] This command is only available in this version of Windows when LPD Print Service is enabled through Windows Features.