$BatchInput (Built-in Mathematica Symbol)

$BatchInput is True if input in the current session is being fed directly to the Mathematica kernel in batch mode.

$CharacterEncodings (Built-in Mathematica Symbol)

$CharacterEncodings gives the list of character encodings that can be used.

$ConfiguredKernels (Built-in Mathematica Symbol)

$ConfiguredKernels is the default list of kernels that are configured to be launched for parallel computing.

$ContextPath (Built-in Mathematica Symbol)

$ContextPath is a global variable that gives a list of contexts, after $Context, to search in trying to find a symbol that has been entered.

$CurrentLink (Built-in Mathematica Symbol)

$CurrentLink is the LinkObject representing the MathLink connection for an external program currently being installed or being called.

$ExportFormats (Built-in Mathematica Symbol)

$ExportFormats gives a list of export formats currently supported in your Mathematica system.

$ImportFormats (Built-in Mathematica Symbol)

$ImportFormats gives a list of import formats currently supported in your Mathematica system.

$KernelCount (Built-in Mathematica Symbol)

$KernelCount gives the number of subkernels available for parallel computations.

$MaxMachineNumber (Built-in Mathematica Symbol)

$MaxMachineNumber is the largest machine-precision number that can be used on a particular computer system.

$MaxNumber (Built-in Mathematica Symbol)

$MaxNumber gives the maximum arbitrary-precision number that can be represented on a particular computer system.