Yes,
I'm setting them under the "Edit" menu, "Set Code Replacements", delimiter is default.
Under the "IPTC Stationary Pad", I'm checking the "IPTC Subject Code" box, clicking on the drop down menu, clicking on the code I want, then in the caption box, I'm entering the code (ex: /mkj64/) plus some text describing the action.
When I finish entering the text box (under Caption). everything is just as I entered it, there is no name substitution. When I click open the info tab again, the Caption box is still the same, with the code there, not a substituted name.