The group that starts with the Lines keyword defines the trace lines to be drawn between nodes in the geometry displays. For the building model example the definition is like this:
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This is the line definition group.
From Node Number, To Node Number.
Lines
1 2
2 3
3 6
6 5
5 4
2 5
7 8
8 9
10 11
11 12
8 11
9 12
5 11
2 8
6 12
3 9
1 4
4 10
10 7
7 1
This group has two fields per record and as many records as there are trace lines in the geometry. The two fields indicate from what node and to what node the trace line should be drawn. In the example a line has to be drawn between node 1 and node 2, between 2 and node 3... etc. There can only be one line definition per record. If a specified node does not exist an error will occur.