diff --git a/unstable/wlr-layer-shell-unstable-v1.xml b/unstable/wlr-layer-shell-unstable-v1.xml
index 90b8bc8..d5cf856 100644
--- a/unstable/wlr-layer-shell-unstable-v1.xml
+++ b/unstable/wlr-layer-shell-unstable-v1.xml
@@ -127,14 +127,19 @@
 
     <request name="set_exclusive_zone">
       <description summary="configures the exclusive geometry of this surface">
-        Requests that the compositor avoids occluding an area of the surface
-        with other surfaces. The compositor's use of this information is
+        Requests that the compositor avoids occluding an area with other
+        surfaces. The compositor's use of this information is
         implementation-dependent - do not assume that this region will not
         actually be occluded.
 
-        A positive value is only meaningful if the surface is anchored to an
-        edge, rather than a corner. The zone is the number of surface-local
-        coordinates from the edge that is considered exclusive.
+        A positive value is only meaningful if the surface is anchored to one
+        edge or an edge and both perpendicular edges. If the surface is not
+        anchored, anchored to only two perpendicular edges (a corner), anchored
+        to only two parallel edges or anchored to all edges, a positive value
+        will be treated the same as zero.
+
+        A positive zone is the number of surface-local coordinates to consider
+        exclusive.
 
         Surfaces that do not wish to have an exclusive zone may instead specify
         how they should interact with surfaces that do. If set to zero, the