how to make add superscript letters to the name of each category bar?

for example in the attachment, I want to display "+" as superscript. Is there any way to do it? many thx!!
JimProuty wrote:
Add \S+ to each element of the text wave.

--Jim Prouty
Software Engineer, WaveMetrics, Inc.

many thx!

may i ask what is the code for italic and normal? i tried f02 and f00 which doesn't work.