line3OpeningDate

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: line3OpeningDate

Indicates the calendar date on which the third line (e.g., a route, service line, or similar system component) was officially opened or began operation.