This option controls how downstream structures are numbered for parallel pipes. Within Lucity™, every pipe must be unique in its upstream and downstream structure numbers. To accommodate this, the upstream structure number on multiple pipes must be given a dummy structure number. Within the map, this is accomplished by assigning "indexes" in the i field for pipes that are in parallel. For instance, if you have the above options set, and you have four pipes that are in parallel.
In Lucity™, these are the pipes you would have:
Upstream Structure = A-1 Downstream Structure = B-1
Upstream Structure = A-1P2 Downstream Structure = B-1
Upstream Structure = A-1P3 Downstream Structure = B-1
Upstream Structure = A-1P4 Downstream Structure = B-1
Note: We have made the "i" index field for parallel pipes optional; however, it is still required for any clients who have parallel pipes drawn in the map.