[Clas_offline] Question about vertex position in CLAS6 BOS banks

[skorodum at jlab.org]

Dear All,

does anyone know how to find x and y positions of the vertex.
I found two sets of variables related to vertex position that look different:

first in EVNT bank
9  X        F  -100.  100.     ! X coordinate of vertex (cm)
10  Y        F  -100.  100.     ! Y coordinate of vertex (cm)

and second in DCPB bank
8  X_v      F  -999.  999.   ! vertex X after fiting to the beam position
9  Y_v      F  -999.  999.   ! vertex Y after fiting to the beam position

What is the difference between them? Both of them do not look like real
beam profile. Does anyone know how to obtain real x and y distribution?

I am asking because I am going to use values x and y as coordinates of the
beam offset in FFREAD card for GSIM (option POSBEAM). Is it a right
approach to take into account the beam offset in the Monte-Carlo?

Thank you in advance.

Best regards,
Iuliia.