Is it correct that Langlands' combinatorial exercise (as he terms it in his paper "[Shimura varieties and the Selberg trace formula](https://publications.ias.edu/sites/default/files/shim-ps.pdf)") is to establish base change identities between orbital integrals of the group $G$ over a number field and twisted orbital integrals over some unramified extension? Or am I completely wrong?

I am trying to understand this part of the Langlands' paper "[On the zeta-functions of some simple Shimura varieties](https://publications.ias.edu/sites/default/files/simpshim-ps.pdf)" without much success...