The following features are demonstrated in this example:
problem type: mixed integer linear programming (vehicle routing)
reading dense (upper triangular) two-dimensional data
sets of tuples
sets indexed by other sets
set operators UNION and DIFF
multiple objectives
INIT option
CARD function
using a colon (:) to select members of a set
aggregation operators SETOF and AND
modeling if-then constraints by using binary variables
symmetry-breaking constraints
MILP solver option SYMMETRY=
calling a solver in a DO UNTIL loop
row generation
.sol variable suffix
connected components
SOLVE WITH NETWORK