Quest 2 calibration with external camera and access to guardian coordinates

I am working on the calibration of the Quest 2 with a physical camera.  I would like to better understand how the Quest 2 establishes the coordinates of its 3D space in relation to the guardian and especially how it either re-establishes or changes this when it is turned off, sleeps or goes outside of the guardian?  Is there a system 'translation vector' that could be read and used to realign local 3D space with the updated Quest 2 3D space?  If not, I am interested in learning how to establish a relationship with or get access to some fixed coordinate in the guardian space such that a translation vector could be calculated.

Any input on this would be appreciated.  I have not been able to find reference details on this via a search - could someone point me in the right direction? If it needs context, then it would be relative to Unity.  I have developed for other platforms but am new to development for the Quest 2 / Unity.