Yes, it does. When you add your note if you look over to the left of your screen you should see a box with the grey header that says Text Format. There are three symbols just above middle in this box. The one on the right is for Add Symbol. Click on that and you get images of symbols to choose from. The one in the top right corner is +/-. If you pause over the symbols you will also see their field codes, in this case <MOD-PM>. If you were to type in this field code you will get the +/- symbol.
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