What is the name of the region between parentheses after the class name in Python?

For a function definition you'd speak of the "arguments" or "signature" of the function but is there a similar name for the list of parent classes and keyword arguments (since __init_subclass__) that can be used for classes? How could I refer to this when writing documentation?

# Parameters, arguments, function signature
#       v----------v
def func(arg1, arg2):
  pass

# Similarly, what's this called?
#        v-----------------------------v
class Cls(Parent, Mixin, mixin_arg=True):
  pass