via_dbid->parent->objType
=>branch
via_dbid->parent->parent
=>nil
说明书中有一句
Table 2-4 Branch Attributes
Attribute Name Type Description
Also includes generic object and figure attributes
children l_dbid List of dbids of the objects that make up branch:
paths, tees, vias, pins and shapes
objType string Type of object, in this case “branch”
parent dbid Always nil
但是查询via是能看到归属的net的