Reference for unit 'System': Variables

`argv`		Pointer to the array of command-line arguments
`DispCallByIDProc`		Callback to perform dispatch interface procedure call by ID.
`envp`		Pointer to the array of environment variables
`ErrOutput`		Alias for StdErr
`ExitCode`		Exit code for the program, will be communicated to the OS on exit.
`InOutRes`		Result of last I/O operation. Read-Only.
`Input`		Standard input text file.
`IsConsole`		`True` for console applications, `False` for GUI applications.
`IsLibrary`		`True` if the current module is a library. Otherwise module is an excutable
`Null`		Null variant
`Output`		Standard output text file.
`RandSeed`		Seed for Random function.
`ReturnNilIfGrowHeapFails`		Describe behaviour if getmem fails.
`StackBottom`		Current stack bottom.
`StackLength`		Maximum stack length.
`StdErr`		Standard diagnostic output text file.
`StdOut`		Alias for Output.
`ThreadID`		Current Thread ID.
`Unassigned`		Unassigned variant.
`VarDispProc`		Callback to perform dispatch interface procedure call by name.
`widestringmanager`