DICOM PS3.3 2020e - Information Object Definitions
C.8.8.25.11 Block and Compensator Data

Similarly to Section C.8.8.25.3, in the case where Snout Position (300A,030D) changes between control points, the scaling factor to be used to convert from DICOM data defined at the isocenter plane (such as Block Data (300A,0106) and Isocenter to Compensator Distances (300A,02E6) ) to the physical dimension of the accessories is purely based on the Isocenter to Compensator Tray Distance (300A,02E4) and Isocenter to Compensator Distances (300A,02E6) defined at the beam level and should not take into account the possible effect of Snout Position (300A,030D) changes between Control Points.

DICOM PS3.3 2020e - Information Object Definitions