Mask information in LRC. Where is it stored? Does the SDK allow me to read and write to it?

I am writing a Python program that analyzes my images and gives me not only feedback about the images but editing tips. Currently it will write a new XMP file based on its findings. What is not included in the XMP file are any masking edits. Where are masking edits and their associated data stored, and are they in a place that I can access programmatically?