[or ] the shortest or most efficient distance from S to Tn [or Um]
[or ] "on-site travel": distance(s) covered "around" Tn [or Um] point
[or ] distance covered between T1 and U1 [or k-th distance between some T and/or U points]
sum of all k distances covered between all T and U points
[or ] weight
the shortest or most efficient return trip distance from S to T1
combined return trip distance from S to T1 and U1 points
adjusted return trip distance from S to T1 (with U1 substracted)
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