How to understand the Date.dat file in the DICOM example

Particles, Track, Event, Run and Biasing
1

Hi geant4ers：
I’ve been doing an experiment recently, and the experiment’s needed to build a human brain model from CT images, so I started to learn the example DICOM. But I don’t quite understand is the Data.dat file provided in the file, I have seen the hint given inside the readme, but this hint message is too abbreviated.
Here is the Data.dat file in this example:

8
3
1
2
3
10
Air 0.207
LungInhale 0.481
LungExhale 0.919
AdiposeTissue 0.979
Breast 1.004
Water 1.043
Muscle 1.109
Liver 1.113
TrabecularBone 1.496
DenseBone 1.654

Also I don’t know where this example is converting a file in dicom format to .g4dcm format.
This question has been bothering me for two weeks and I really need your help, thank you for your answers.