You would usually have a function called load level. The function reads in the first level from data statements. say something like
Data 1 ; level number Data 4 ; number of entities Data 30,0,40 Data 90,0,60 Data 330,0,40 Data 10,0,140 Data 2 ; level number Data 2 ; number of entities Data 130,10,120 Data 70,30,110