MATLAB stepresp and TDR

Here is an explanation of how to simulation TDR and TDT from S parameter in MATLAB https://www.mathworks.com/help/rf/examples/modeling-a-high-speed-backplane-part-3-4-port-s-parameters-to-differential-tdr-and-tdt.html

The out-of-box TDR waveform doesn't look the same as a regular TDR waveform from any measurement. For example, as shown here: http://www.mohr-engineering.com/documents/CT100_OPMAN/CT100_TDR_Cable_Tester_Guide.php

I think the key difference is the termination at the port of S parameter. Since it is not specified as using stepresp, what is actually happening when doing stepresp in MATLAB? Can I specify some kind of termination? Thank you.