Confusion about the implication of the code

Hi, I am a student in learning two-country model with a paper and its code which are listed in Working Papers | Dynare
I feel confused about the fomular in line 66 and 69 in the dynare code, I cannot find the corresponding part in the paper ,could anyone tell me the implication of these two fomular?
Thanks for any advice! Best wishes to you!

The fomulars are illustrated as follows:

The dynare code is here:
no3inTCM.mod (4.6 KB)

The paper is here:
3.Tae-Seok, Eiji, 2013, Productivity shocks and monetary policy in a two-country model, Dynare working papers.pdf (348.3 KB)

Those are the real natural rates of interest defined below equation (29)

Thank you very much!