Specifying predefined schematic attributes to manage the schematic topology
Specifying the origin and extremity nodes for schematic links
The origin and extremity nodes for the schematic links contained in schematic diagrams are generally automatically managed by schematic builders. For example, the Standard and Network Dataset builders are able to decode the topology of the geometric network or network dataset from the input GIS features on which the diagram generation is based, and they automatically display connected schematic links. For the XML builder, the <FromNode> and <ToNode> XML tags are mandatory for any LinkFeature XML item in the input XML data, and they are used to connect the related schematic links.
For Standard builder diagrams that are entirely built from custom queries, the origin and extremity nodes are not initialized by default for the schematic links. In that case, the OriginNode and ExtremityNode predefined attributes need to be configured on each link schematic feature class to determine the links' origin and extremity nodes.
- The OriginNode predefined attribute is expected to return the origin node identifier for each schematic link.
- The ExtremityNode predefined attribute is the one to use for specifying the link extremity node identifier.
Note:- For schematic links built from custom queries, the OriginNode and ExtremityNode attributes are mandatory attributes that need to be specified on each link schematic feature class. When these attributes are missing, no schematic link can be correctly displayed in the diagrams.
- For schematic links contained in diagrams generated by the XML or Network Dataset builder, or generated by the Standard builder when it operates from GIS features highlighted in a map after a selection or trace operation, these predefined attributes don't need to be specified, since the builder is able to initialize the topology from the input data on which they operate. But, when they are configured, they overwrite the information initialized by default by the builder.
- Those predefined schematic attributes are also mandatory attributes for sublink schematic feature classes. In that case, each returned attribute value may correspond to either a node identifier or a node-on-link identifier.
Managing schematic link connections to ports
Schematic nodes contained in schematic diagrams can be represented by a composed symbol that contains ports. No schematic builder automatically manages schematic feature link connections to ports, by default. But, when a diagram is edited, whatever the builder that builds it, the Reconnect Schematic Link tool 
can be used to manually reconnect any schematic link to any specific port on its origin or extremity schematic node. The reconnections that have been manually specified can then be stored in the link schematic feature class in the schematic dataset.
Moreover, there are two predefined attributes that can be configured to automatically initialize port connections for schematic links—OriginPortNumber and ExtremityPortNumber.
- The OriginPortNumber predefined attribute is expected to return the link origin port number on the symbol used to display the origin node.
- The ExtremityPortNumber predefined attribute is the one to use for specifying the link extremity port number on the symbol used to display the extremity node.
If you have the information clearly stored in your database, or if connection ports can be deduced from other information somewhere, configuring the OriginPortNumber and ExtremityPortNumber predefined attributes on schematic feature link classes allows you to initialize schematic connections in a very precise way. Depending on the evaluation mode configured for the predefined attributes, this new topological data will be reflected on the schematic features contained in the generated schematic diagrams after these diagrams have been updated or when they are loaded in memory.