diff --git a/core/api/src/main/java/org/onosproject/ui/topo/PropertyPanel.java b/core/api/src/main/java/org/onosproject/ui/topo/PropertyPanel.java
index 87b6839..03ff2a3 100644
--- a/core/api/src/main/java/org/onosproject/ui/topo/PropertyPanel.java
+++ b/core/api/src/main/java/org/onosproject/ui/topo/PropertyPanel.java
@@ -35,6 +35,7 @@
     private String typeId;
     private String id;
     private List<Prop> properties = new ArrayList<>();
+    private List<Button> buttons = new ArrayList<>();
 
     /**
      * Constructs a property panel model with the given title and
@@ -174,6 +175,16 @@
         return properties;
     }
 
+    /**
+     * Returns the list of button descriptors.
+     *
+     * @return the button list
+     */
+    // TODO: consider protecting this?
+    public List<Button> buttons() {
+        return buttons;
+    }
+
     // == MUTATORS
 
     /**
@@ -226,6 +237,17 @@
         return this;
     }
 
+    /**
+     * Adds a button descriptor with the given identifier, to the panel data.
+     *
+     * @param id button identifier
+     * @return self, for chaining
+     */
+    public PropertyPanel addButton(String id) {
+        buttons.add(new Button(id));
+        return this;
+    }
+
     // ====================
 
 
@@ -300,4 +322,29 @@
         }
     }
 
+    /**
+     * Button descriptor. Note that these work in conjunction with
+     * "buttons" defined in the JavaScript code for the overlay.
+     */
+    public static class Button {
+        private final String id;
+
+        /**
+         * Constructs a button descriptor with the given identifier.
+         *
+         * @param id button identifier
+         */
+        public Button(String id) {
+            this.id = id;
+        }
+
+        /**
+         * Returns the identifier for this button.
+         *
+         * @return button identifier
+         */
+        public String id() {
+            return id;
+        }
+    }
 }
diff --git a/core/api/src/main/java/org/onosproject/ui/topo/TopoConstants.java b/core/api/src/main/java/org/onosproject/ui/topo/TopoConstants.java
index ca3ce5f..d44ba9f 100644
--- a/core/api/src/main/java/org/onosproject/ui/topo/TopoConstants.java
+++ b/core/api/src/main/java/org/onosproject/ui/topo/TopoConstants.java
@@ -73,4 +73,37 @@
         public static final String STOP = "stop";
         public static final String CLOUD = "cloud";
     }
+
+    /**
+     * Defines constants for property names on the default summary and
+     * details panels.
+     */
+    public static final class Properties {
+        // summary panel
+        public static final String DEVICES = "Devices";
+        public static final String LINKS = "Links";
+        public static final String HOSTS = "Hosts";
+        public static final String TOPOLOGY_SSCS = "Topology SCCs";
+        public static final String INTENTS = "Intents";
+        public static final String TUNNELS = "Tunnels";
+        public static final String FLOWS = "Flows";
+        public static final String VERSION = "Version";
+
+        // device details
+        public static final String URI = "URI";
+        public static final String VENDOR = "Vendor";
+        public static final String HW_VERSION = "H/W Version";
+        public static final String SW_VERSION = "S/W Version";
+        public static final String SERIAL_NUMBER = "Serial Number";
+        public static final String PROTOCOL = "Protocol";
+        public static final String LATITUDE = "Latitude";
+        public static final String LONGITUDE = "Longitude";
+        public static final String PORTS = "Ports";
+
+        // host details
+        public static final String MAC = "MAC";
+        public static final String IP = "IP";
+        public static final String VLAN = "VLAN";
+    }
+
 }