If you want to assign a symbol name (e.g., address of a Windows function or a Windows global variable) to a script engine variable, you should specify the module name along with a bang '!' character; otherwise, it's interpreted as a variable name. For example,
x = ExAllocatePoolWithTag; is equal to assigning the a script engine variable named ExAllocatePoolWithTag to a variable named x. However,
x = nt!ExAllocatePoolWithTag; means assigning the function address from the nt module to the x variable.