A sublink is a particular link schematic feature that exists as part of another link. It connects one node on link to one of its related link's extremity node or connects two nodes on link. Sublinks are completely dependent on the link they are related to. Selecting and moving a link automatically selects and moves its sublinks. The destruction of the link causes the automatic destruction of its sublinks.
Defining nodes on link and sublinks for your links is often useful when you have to graphically display a line that is composed of different sections. For example, in the electrical world, there are electrical lines that combine an overhead part and underground part along their path. In this case, it could be useful to graphically distinguish the overhead part from the underground one using sublinks and nodes on link.
Sublink schematic feature class creation
Configuring a sublink schematic feature class or a link schematic feature class is similar. Like for a link schematic feature class, predefined attributes must be specified on the sublink schematic feature class.
All predefined attribute names that can be configured for a link schematic feature class—for example, OriginNode and ExtremityNode—can be configured for a sublink schematic feature class. But there is another predefined attribute available for sublinks: ReferenceLink. This attribute is used to identify the schematic link identifier the sublink is related to.
Learn more about predefined attribute names for a Sub Link schematic feature class