I started using non-breaking spaces between a number and a unit of measure (10_ft), and within a name (Dr._John_Smith). I like the "look" of using non-breaking spaces to prevent titles from wrapping, but I don't know if it's technically correct or not. Is there a hard rule for this, or it a matter of style? Are their other circumstances when non-breaking spaces are usual?
Just in case it's news to anyone: you can enter a non-breaking space with Ctrl-Shift-Space in Word and Outlook, and possibly other applications.