In reading about Nasdaq, it states Nasdaq ticker s

In reading about Nasdaq, it states Nasdaq ticker symbols have 4 letters-such as Microsoft is MSFT. It says some may have an identifying 5th symbol, mainly for foreign companies or bankruptcy, etc. The H.R.I., Rx seems unusual according to what I read. It makes no difference to me, just thought that was an unusual symbol. They can use "TTILTS" (the train is leaving the station) as far as I am concerned. Maybe some of you can straighten me out. JMO