diff --git a/man/ostree-prepare-root.xml b/man/ostree-prepare-root.xml
index 53aad8cd..9117c340 100644
--- a/man/ostree-prepare-root.xml
+++ b/man/ostree-prepare-root.xml
@@ -117,6 +117,24 @@ License along with this library. If not, see .
etc.transient
A boolean value; the default is false. If this is set to true, then the /etc mount point is mounted transiently i.e. a non-persistent location.
+
+ root.transient
+ A boolean value; the default is false.
+ If this is set to true, then the / filesystem will be a writable overlayfs,
+ with the upper directory being a hidden directory (in the underlying system root filesystem) that will persist across reboots by default.
+ However, changes will be discarded on OS updates!
+
+
+ Enabling this option can be very useful for cases such as packages (dpkg/rpm/etc) that write content into /opt,
+ particularly where they expect the target to be writable at runtime. To make that work, ensure that your /opt
+ directory is *not* a symlink to /var/opt, but is just an empty directory.
+
+
+ Note the /usr mount point remains read-only by default. This option is independent of etc.transient and sysroot.readonly;
+ it is supported for example to have root.transient=true but etc.transient=false in which case changes to /etc continue
+ to persist across updates, with the default OSTree 3-way merge applied.
+
+
composefs.enabled
This can be yes, no. maybe or