AbstractThe focus of this comment is to correct potential misconceptions regarding the application of perfectly matched layer (PML) absorbing media to terminating inhomogeneous media within the finite‐difference time‐domain (FDTD) method. Initially, it is demonstrated that the PML is material independent by nature. That is, by specifying the constitutive parameters to be independent of the host material medium, both the split‐field form and the anisotropic form (or unsplit form) of the PML are materially independent. It is then demonstrated that the split‐field and nonsplit‐field forms of the “materially independent PML” (MIPML) proposed earlier are identical to Berenger's split‐field PML and the anisotropic PML formulations, respectively, after a simple scaling of the conductivity by a constant. While this validates the MIPML, it also illustrates that the MIPML is a subset of previously proven PML methods. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 289–291, 2001.