(anon451647 writes)
The hard problem here is that it is impossible to predict what kind of material will be in front and back matter, here you are limited only by your imagination. Currently if you want to check this material you have to decide what you want to be there and make your own stylesheet as described in these Help topics.
“How do I create a separate stylesheet for front and back matter?” “How does the stylesheet specify where a marker is allowed to occur?”
This is a non-trivial task. It would be a good thing if it were done once per entity (probably by the typesetter for the entity) and passed around to all the projects in that entity.
If all you want is to just to use any current marker at any location in the front and back matter you can place the “http://update.ubs-icap.org/Paratext/frtbak.sty” file in your “My Paratext Projects/XYZ” project directory (where XYZ is the project name). It is just the standard usfm.sty with all of the \Rank and \OccursUnder lines removed.