What does a sticker with the abbreviation hsr mean?

HSR is Hamilton Street Railway; the public transit company of City of Hamilton, Ontario, Canada. Check:
http://www.myhamilton.ca/myhamilton/CityandGovernment/CityServices/Transit
http://en.wikipedia.org/wiki/Hamilton_Street_Railway

The sticker is a special bus pass issued for full-time students attending McMaster University; Check: http://www.mcmaster.ca/