[Freesurfer] How are Vertex RAS coordinates calculated in TKsurfer

Dear FS experts:

I am studying the coordinate system in FS. I met a problem that confused me. I run tksurfer: tksurfer fsaverage lh inflated. Then I chose a point on surface. It showed that the Vertex Index is 80321, and the Vertex RAS is (-38.53 9.05 40.01). I thought that the Vertex RAS is just obtained from the lh.inflated file. But I run: mris_info --v 80321 .\fsaverage\surf\lh.inflated. It showed that coordinate is (-18.4 40.8 32.7).

I have no idea that how the Vertex RAS is calculated in Tksurfer. Maybe is there a transform matrix between the two coordinates ? If so, how can i get the transform matrix ?

Best,

Zhiliang