Question about conducting multiple regression on SPSS.

Hi! Friends, does anyone know how does the author proved perceived role clarity, intrinsic motivation, job involvement, and IWB were related with each other?

In his results, he made model 1 to model 6 to prove that ( the attached photo) with multiple regression analysis on SPSS. He mentioned “Table IV summarizes the multiple regression analysis results” ( showed on the picture below)

However, as we all know that we can only input 1 dependent variable in linear regression on SPSS. I don’t quite understand how he could make the table below, and prove all variable are related to each other. Does that means he needs to calculate 6 times of linear regression analysis on SPSS (ex, perceived role clarity vs intrinsic motivation; intrinsic motivation vs job involvement, job involvement vs IWB…etc) Or there is a simple way to calculate model 1 to model 6 on SPSS in one times. And where does the name model 1 to model 6 come from ? are those set by SPSS, or the author sets them on his own? 1652900190928.png 1652900205862.png