The following data set and macro variable contain the additional input data that are used in this example:
/* missing expansion_prerequisite indicates no prerequisite */ data expansion_data; input expansion expansion_depot $10. expansion_amount expansion_cost expansion_prerequisite; datalines; 1 Birmingham 5 18000 . 2 Birmingham 5 8000 1 3 Manchester 5 20000 . 4 Manchester 5 5000 3 5 Plymouth 5 19000 . ; %let max_num_expansions = 3;