Frederic, I'm all set. I found that for HTML, the command is <br>, and I need to set it off with double quotes. My final working expression only shows the Next Action and Summary Notes literals if there is data in either of those fields. If there is data, then it prints the literals and bolds them. A carriage return is insterted between the two pieces of data, but only on the condition that Next Action, which comes first, actually has data in it.
=Iif(Trim(Fields!Next_x0020_Action.Value)<>"","<b>Next Action: </b>", "")& Fields!Next_x0020_Action.Value & Iif(Trim(Fields!Next_x0020_Action.Value)<>"","<br>","")& (Iif(Trim(Fields!Issue_x0020_Summary.Value)<>"", "<b>Summary Notes: </b>","")) & Fields!Issue_x0020_Summary.Value