I don't think you do. And starting a new thread would be better, actually, along with more details of what you want in the marker. I'll branch this to a new discussion, and you can reply with the gory details of what you want to see and your version of ID.
I'm creating a single document and trying to use sections as chapters. I can see how to use the section marker to show manually added text (as I stated above) for running footers and such, but how would I add automatically updating section numbers (faux chapter numbers but in a single doc)? I'm thinking it's not possible after googling and forum searching.
Rather than trying to do it with section prefixes, why not assign a unique paragraph style to the chapter heading that includes a Numbered List, and set the number to include "Chapter" or other text before the actual number. You can then pick up this text using a running header variable for the header or footer on subsequent pages.