Understanding the dataset



Hi all!
I am trying to deploy the channel attribution package in R, following the steps provided in the article “A Beginner’s Guide to Channel Attribution Modeling in Marketing (using Markov Chains, with a case study in R)”.

I have troubles understanding the dataset that is used in the example.
Could you please explain:
1)what R05A.01,R05A.02, etc. headers represent and what can be used to substitute them
2) what does channel “20” represent? I am seeing it says “#20 – customer has decided which device to buy” , but why is it then included as a channel in the attribution model (on the graph)?

Thanks so much!