HTC One M9 - Manual (Page 68)

Your Phone Interface 55
Status Bar Layout
Main Notification Icons
Icon Notification
Mobile Hotspot is on
New text or MMS message
New voicemail
New Gmail message
New email
Event
Music is playing
Power saver mode is on
General notification (for example, sync error)
Wi-Fi is on and wireless networks are available
More notifications available (tap to view)
Missed call
Call in progress
Downloading
Uploading
Waiting to upload
USB connection
Update successful
New Sprint Zone message