In the sympy documentation about quatenions https://docs.sympy.org/latest/modules/algebras.html#sympy.algebras.Quaternion the quatenion constructor is defined as:

class sympy.algebras.Quaternion(a=0, b=0, c=0, d=0, real_field=True, norm=None)

What is the meaning of keyword argument real_field=True?

Thanks in advance for the answers.

Kind regards

Klaus