isSuburbanRouteOf

Given a predicate that represents a relationship or action between entities, generate a one-sentence description explaining its meaning.  
# Instructions
Focus on describing the relationship, not the entities themselves. 
# Response Format
Begin the description with \' Indicates...\'

Predicate: isSuburbanRouteOf

Indicates that a given route functions as a suburban segment or service line belonging to, or operating as part of, a larger primary route or network.