Where is file size stored in an APFS volume?

I can read an APFS container and volume and find the inode for a file successfully but I cannot find the size of a file, in bytes, anywhere in the "Apple File System Reference" documentation, 2020-06-22 version. The best I can see is the number of 4K blocks the file has in it's extents list.

Can anyone point me in the right direction.

Thanks
Where is file size stored in an APFS volume?
 
 
Q