diff --git a/libcroesor/backend-manager.c b/libcroesor/backend-manager.c
index 65787b15ff231c8e93a3bb8655a6ac617185184c..4b97e96259fad721f232800878eb7cf7b02a7db4 100644
--- a/libcroesor/backend-manager.c
+++ b/libcroesor/backend-manager.c
@@ -19,6 +19,14 @@
 
 #include "backend-manager.h"
 
+/**
+ * SECTION:backend-manager
+ * @short_description: An implementation of #CsrPeerManager which manages a single peer: the daemon.
+ *
+ * See also #CsrBackendManager
+ *
+ * #backend-manager is available since 0.4.0
+ */
 
 static void            csr_backend_manager_peer_manager_init          (CsrPeerManagerInterface  *iface);
 static void            csr_backend_manager_dispose                    (GObject                  *object);
diff --git a/libcroesor/backend-manager.h b/libcroesor/backend-manager.h
index 90a3ae3af0b5e6cee241663aa0b69605d49becab..66ae9951d6befc20a0b3016d20e513f19d3d295d 100644
--- a/libcroesor/backend-manager.h
+++ b/libcroesor/backend-manager.h
@@ -18,6 +18,13 @@
 
 G_BEGIN_DECLS
 
+/**
+ * CSR_TYPE_BACKEND_MANAGER:
+ *
+ * Retrieve the #CsrBackendMAnager type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_BACKEND_MANAGER csr_backend_manager_get_type ()
 G_DECLARE_FINAL_TYPE (CsrBackendManager, csr_backend_manager, CSR,
                       BACKEND_MANAGER, GObject)
diff --git a/libcroesor/backend.c b/libcroesor/backend.c
index f6294fbe389c6a0316abcdd4b217219735b6b0cf..72f42cb68fc6e7016e301dfd62cfdec64ca84252 100644
--- a/libcroesor/backend.c
+++ b/libcroesor/backend.c
@@ -22,9 +22,24 @@
 #include "libcroesor/vehicle-manager.h"
 #include "libcroesor/vehicle-service.h"
 
+/**
+ * SECTION:backend
+ * @short_description: Implementation of a backend
+ *
+ * A skeleton implementation of a backend for the vehicle device daemon.
+ * See also #CsrBackend
+ *
+ * #backend is available since 0.2.0
+ */
 
 /* These errors do not need to be registered with
  * g_dbus_error_register_error_domain() as they never go over the bus. */
+
+/**
+ * csr_backend_error_quark:
+ *
+ * Return a GQuark from the csr-backend-error-quark string
+ */
 GQuark
 csr_backend_error_quark (void)
 {
diff --git a/libcroesor/backend.h b/libcroesor/backend.h
index 5468dc5fd53c82d8b47a98715fd90451148c8211..f619decd0fd302fd29565c0539d17d21bb924297 100644
--- a/libcroesor/backend.h
+++ b/libcroesor/backend.h
@@ -43,6 +43,13 @@ typedef enum
   CSR_BACKEND_ERROR_VEHICLE_UNREGISTERED,
 } CsrBackendError;
 
+/**
+ * CSR_TYPE_BACKEND:
+ *
+ * Retrieve the #CsrBackend type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_BACKEND csr_backend_get_type ()
 G_DECLARE_FINAL_TYPE (CsrBackend, csr_backend, CSR, BACKEND, CsrService)
 
diff --git a/libcroesor/clock.h b/libcroesor/clock.h
index c64b29a02f996f7f5a18c797af39d7e03406d8e1..3f3d87ff8c86b36f366c43bcc2664540d8de9d36 100644
--- a/libcroesor/clock.h
+++ b/libcroesor/clock.h
@@ -16,6 +16,15 @@
 
 G_BEGIN_DECLS
 
+/**
+ * SECTION:clock
+ * @short_description: Clock management function
+ *
+ * See also #CsrClockFunc
+ *
+ * #clock is available since 0.4.0
+ */
+
 /**
  * CsrClockFunc:
  * @user_data: user data to pass to the clock
diff --git a/libcroesor/docs/libcroesor-docs.sgml b/libcroesor/docs/libcroesor-docs.sgml
index 2e34b2d4f72f2f432b1db37f4bfc7c5f54d76665..f8aa3cc7f0b508693aeec109facec47d638b341d 100644
--- a/libcroesor/docs/libcroesor-docs.sgml
+++ b/libcroesor/docs/libcroesor-docs.sgml
@@ -1,23 +1,14 @@
 <?xml version="1.0"?>
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
-               "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd"
-[
-  <!ENTITY % local.common.attrib "xmlns:xi  CDATA  #FIXED 'http://www.w3.org/2003/XInclude'">
-  <!ENTITY % gtkdocentities SYSTEM "xml/gtkdocentities.ent">
-  %gtkdocentities;
-]>
+               "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
 <book id="index" xmlns:xi="http://www.w3.org/2003/XInclude">
   <bookinfo>
-    <title>&package_name; Reference Manual</title>
-    <releaseinfo>
-      for &package_string;.
-      The latest version of this documentation can be found on-line at
-      <ulink role="online-location" url="http://[SERVER]/&package_name;/index.html">http://[SERVER]/&package_name;/</ulink>.
-    </releaseinfo>
+    <title>libcroesor Reference Manual</title>
   </bookinfo>
 
+  <xi:include href="overview.xml"/>
   <chapter>
-    <title>[Insert title here]</title>
+    <title>libcroesor APIs</title>
     <xi:include href="xml/backend.xml"/>
     <xi:include href="xml/backend-manager.xml"/>
     <xi:include href="xml/clock.xml"/>
diff --git a/libcroesor/docs/overview.xml b/libcroesor/docs/overview.xml
new file mode 100644
index 0000000000000000000000000000000000000000..3130267e0d6f83bb7e02529c4f6244bab3761ad4
--- /dev/null
+++ b/libcroesor/docs/overview.xml
@@ -0,0 +1,30 @@
+<section xml:id="libcroesor-overview">
+  <title>libcroesor Overview</title>
+  <para>
+    Mail the maintainers (<email>rhosydd@apertis.org</email>)
+  </para>
+  <para>
+    libcroesor is a library for use within the Rhosydd daemon and its backends (both internal and external backends). It provides utility classes for implementing collections of attributes and zones in vehicles, and exposing them over D-Bus to be consumed. The vehicles exposed by Rhosydd backends are consumed by the Rhosydd daemon itself, which aggregates them and exposes them to applications.
+  </para>
+  <para>
+    Each backend exposes zero or more vehicles. The main interface for building a backend is the <ulink role="online-location" url="#CsrBackend">CsrBackend</ulink> class, which sets up the necessary D-Bus connection, and provides a <ulink role="online-location" url="#CsrVehicleManager">CsrVehicleManager</ulink> which the backend can use to expose its vehicles on the bus. Typically, the bulk of the implementation of a backend will be in building a class which implements <literal>RsdVehicle</literal> to expose the backend’s vehicle. The <ulink role="online-location" url="#CsrStaticVehicle">CsrStaticVehicle</ulink> class is provided as a basic implementation suitable for backends which need to expose vehicles with a fixed set of attributes whose values do not change over time.
+  </para>
+  <para>
+    The implementation of an <literal>RsdVehicle</literal> to expose attributes from physical components in a vehicle depends on how those components are exposed to the automotive domain. All Rhosydd backends run in the consumer entertainment (CE) domain so, typically, a Rhosydd backend will need to use the inter-domain connection to retrieve sensor data from, and to send actuator commands to, the automotive domain. These implementation details are vehicle-specific; hence all libcroesor and librhosydd can do is provide the <literal>RsdVehicle</literal> interface to implement.
+  </para>
+  <para>
+    Within the daemon, vehicles from the backends are aggregated by their IDs: if two backends expose a vehicle with the same ID, those two vehicles are exposed as a single aggregate vehicle by the backend. This means that multiple backends can be used to provide different attributes for the //same// vehicle, if that suits the architecture in the automotive domain. For example, one backend could expose all attributes which require communication over the vehicle’s CAN bus; and another backend could expose all attributes which are associated with hardware directly connected to the CE domain. If all these attributes are exposed on <literal>RsdVehicle</literal> objects with the same ID, they will be aggregated to form a single vehicle to be exposed to applications. This allows Rhosydd backends to be compartmentalised for security purposes, rather than requiring a monolithic backend which has access to all hardware and buses in the vehicle.
+  </para>
+  <para>
+    When two vehicles are aggregated, their zone hierarchies are combined to form an aggregate zone hierarchy which includes all zones from both vehicles. If the vehicles define the same zone, a single instance of that is present in the aggregate hierarchy (since a zone is a path and nothing more).
+  </para>
+  <para>
+    Their attribute lists are combined to form an aggregate attribute list: all the attributes for a given zone from both vehicles are included in the aggregate attribute list. If both vehicles define the same attribute in a given zone, that is an error and one or both of the backends providing those vehicles will be disconnected from the daemon. In future, the system may permit duplicate attributes to be defined, and would combine their values in the aggregate attribute list; so do not rely on the current semantics.
+  </para>
+  <para>
+    The daemon will forward signals from the backends to the aggregated vehicles, signalling updates to attributes and metadata.
+  </para>
+  <para>
+    The daemon will also apply security policy to the vehicles it exposes to applications, reducing the availability of a given attribute if an application is not permitted to access it. This is pending implementation, and its semantics will be defined more rigorously in future.
+  </para>
+</section>
diff --git a/libcroesor/peer-manager.c b/libcroesor/peer-manager.c
index d68d16bae15f5758ca6c1d54ec1e08aceaafdfb0..0ad659b2031bc3c06599f35acd2e00d64c4e6343 100644
--- a/libcroesor/peer-manager.c
+++ b/libcroesor/peer-manager.c
@@ -16,6 +16,15 @@
 
 #include "peer-manager.h"
 
+/**
+ * SECTION:peer-manager
+ * @short_description: An object instance which implements #CsrPeerManagerInterface.
+ *
+ * See also #CsrPeerManager
+ *
+ * #peer-manager is available since 0.2.0
+ */
+
 G_DEFINE_INTERFACE (CsrPeerManager, csr_peer_manager, G_TYPE_OBJECT)
 
 static void
@@ -137,13 +146,12 @@ csr_peer_manager_ensure_peer_info_finish (CsrPeerManager  *peer_manager,
   //return g_steal_pointer (&retval);
 }
 
-/*
+/**
  * csr_peer_manager_check_authorization_async:
  * @peer_manager: a #CsrPeerManager
  * @sender: D-Bus unique name of the peer which is making a request
  * @connection: #GDBusConnection associated with @sender
  * @action_id: ID of the polkit action to check for authorisation
- * @details: populated #PolkitDetails object to pass to the authorisation check
  * @cancellable: (nullable): a #GCancellable, or %NULL
  * @callback: callback to call once the check is complete
  * @user_data: data to pass to @callback
diff --git a/libcroesor/peer-manager.h b/libcroesor/peer-manager.h
index e4775ad4bfc6caa1986441cdf31e7d8a31d5704e..3f5e9335a5e242a7606b1a9bcdf0680831d026f8 100644
--- a/libcroesor/peer-manager.h
+++ b/libcroesor/peer-manager.h
@@ -24,7 +24,22 @@ G_BEGIN_DECLS
  *
  * Since: 0.4.0
  */
+/**
+ * CSR_TYPE_PEER_MANAGER:
+ *
+ * Retrieve the #CsrPeerManager type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_PEER_MANAGER csr_peer_manager_get_type ()
+
+/**
+ * CsrPeerManager:
+ *
+ * An object instance which implements #CsrPeerManagerInterface.
+ *
+ * Since: 0.4.0
+ */
 G_DECLARE_INTERFACE (CsrPeerManager, csr_peer_manager, CSR,
                      PEER_MANAGER, GObject)
 
diff --git a/libcroesor/service.c b/libcroesor/service.c
index 9d5167a874756a634650d501fdd3d586a6273523..dcd8f9080407d9c29a9b25f54fff02b9cd41422a 100644
--- a/libcroesor/service.c
+++ b/libcroesor/service.c
@@ -21,9 +21,23 @@
 #include "libcroesor/service.h"
 #include "libinternal/logging.h"
 
+/**
+ * SECTION:service
+ * @short_description: A skeleton implementation of a system service
+ *
+ * See also #CsrService
+ *
+ * #service is available since 0.2.0
+ */
 
 /* These errors do not need to be registered with
  * g_dbus_error_register_error_domain() as they never go over the bus. */
+
+/**
+ * csr_service_error_quark:
+ *
+ * Return a GQuark from the csr-service-error-quark string
+ */
 GQuark
 csr_service_error_quark (void)
 {
diff --git a/libcroesor/service.h b/libcroesor/service.h
index bcde0b3c0895030d566e38a366eb9941d2bc74ed..eea22c2759cd9f32a330c02401e0b54260d0f05e 100644
--- a/libcroesor/service.h
+++ b/libcroesor/service.h
@@ -49,9 +49,26 @@ typedef enum
   CSR_SERVICE_ERROR_INVALID_ENVIRONMENT,
 } CsrServiceError;
 
+/**
+ * CSR_TYPE_SERVICE:
+ *
+ * Retrieve the #CsrService type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_SERVICE csr_service_get_type ()
 G_DECLARE_DERIVABLE_TYPE (CsrService, csr_service, CSR, SERVICE, GObject)
 
+/**
+ * CsrServiceClass:
+ * @parent_class: the parent class.
+ * @get_main_option_entries: callback to get the main option entries.
+ * @startup_async: callback for startup async.
+ * @startup_finish: callback for startup finish.
+ * @shutdown: callback for shutdown.
+ *
+ * Probably does something awesome.
+ */
 struct _CsrServiceClass
 {
   GObjectClass parent_class;
@@ -67,12 +84,16 @@ struct _CsrServiceClass
                           GError             **error);
   void (*shutdown)       (CsrService          *service);
 
+  /*< private >*/
   gpointer padding[12];
 };
 
-CsrService *csr_service_new              (const gchar   *object_path,
+
+// This function has no implementation
+/*CsrService *csr_service_new              (const gchar   *object_path,
                                           const gchar   *translation_domain,
                                           const gchar   *summary);
+*/
 void        csr_service_add_option_group (CsrService    *self,
                                           GOptionGroup  *group);
 
diff --git a/libcroesor/static-vehicle.c b/libcroesor/static-vehicle.c
index 8b76ebab1a32323b5a0600b7a2283ad2e8c2dfca..d250b39de9defa259f9f37484fda6a9ab15c0d97 100644
--- a/libcroesor/static-vehicle.c
+++ b/libcroesor/static-vehicle.c
@@ -20,6 +20,14 @@
 #include "librhosydd/types.h"
 #include "librhosydd/vehicle.h"
 
+/**
+ * SECTION:static-vehicle
+ * @short_description: An implementation of #RsdVehicle.
+ *
+ * See also #CsrStaticVehicle
+ *
+ * #static-vehicle is available since 0.1.0
+ */
 
 static void csr_static_vehicle_vehicle_init (RsdVehicleInterface *iface);
 static void csr_static_vehicle_dispose      (GObject             *object);
diff --git a/libcroesor/static-vehicle.h b/libcroesor/static-vehicle.h
index b87ca44bc5f3893d331b8ad273ac37a1b74eded3..aed9983ad21dbeff4ba6f9ebf9b75d3b5c608cf9 100644
--- a/libcroesor/static-vehicle.h
+++ b/libcroesor/static-vehicle.h
@@ -18,6 +18,13 @@
 
 G_BEGIN_DECLS
 
+/**
+ * CSR_TYPE_STATIC_VEHICLE:
+ *
+ * Retrieve the #CsrStaticVehicle type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_STATIC_VEHICLE csr_static_vehicle_get_type ()
 G_DECLARE_FINAL_TYPE (CsrStaticVehicle, csr_static_vehicle, CSR,
                       STATIC_VEHICLE, GObject)
diff --git a/libcroesor/subscription-manager.c b/libcroesor/subscription-manager.c
index 1c9cccb531e3dd1deefa7d15b3c3ab95806dd9b9..d9d908070857b961da8782dad3b7d6d86a6a89b1 100644
--- a/libcroesor/subscription-manager.c
+++ b/libcroesor/subscription-manager.c
@@ -17,6 +17,14 @@
 #include "librhosydd/subscription.h"
 #include "librhosydd/vehicle.h"
 
+/**
+ * SECTION:subscription-manager
+ * @short_description: A manager object which stores the sets of subscriptions
+ *
+ * See also #CsrSubscriptionManager
+ *
+ * #subscription-manager is available since 0.2.0
+ */
 
 static void csr_subscription_manager_dispose (GObject *object);
 
diff --git a/libcroesor/subscription-manager.h b/libcroesor/subscription-manager.h
index 3c0f4a0ab7805ef50626ef7cfd3fee361fa3a8a9..8bfd4eaef8c4b9dcb2d3a2a6e8ae9d9a7253ba38 100644
--- a/libcroesor/subscription-manager.h
+++ b/libcroesor/subscription-manager.h
@@ -18,6 +18,13 @@
 
 G_BEGIN_DECLS
 
+/**
+ * CSR_TYPE_SUBSCRIPTION_MANAGER:
+ *
+ * Retrieve the #CsrSubscriptionManager type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_SUBSCRIPTION_MANAGER csr_subscription_manager_get_type ()
 G_DECLARE_FINAL_TYPE (CsrSubscriptionManager, csr_subscription_manager, CSR,
                       SUBSCRIPTION_MANAGER, GObject)
diff --git a/libcroesor/vehicle-manager.c b/libcroesor/vehicle-manager.c
index 3f00d6bbc72ad2d12f99f4af50ade3e47115cc86..b214b2f5751a59c796ae1f0f9bc9c3a8cd51d298 100644
--- a/libcroesor/vehicle-manager.c
+++ b/libcroesor/vehicle-manager.c
@@ -16,6 +16,14 @@
 #include "libinternal/logging.h"
 #include "librhosydd/vehicle.h"
 
+/**
+ * SECTION:vehicle-manager
+ * @short_description: A manager object which stores a set of #RsdVehicles
+ *
+ * See also #CsrVehicleManager
+ *
+ * #vehicle-manager is available since 0.1.0
+ */
 
 static void csr_vehicle_manager_dispose      (GObject      *object);
 
diff --git a/libcroesor/vehicle-manager.h b/libcroesor/vehicle-manager.h
index b196798c93150098f3aa239d451a1018f8feecb0..3f454672cf4965231599aeedd0b974b9efe7a325 100644
--- a/libcroesor/vehicle-manager.h
+++ b/libcroesor/vehicle-manager.h
@@ -18,6 +18,13 @@
 
 G_BEGIN_DECLS
 
+/**
+ * CSR_TYPE_VEHICLE_MANAGER:
+ *
+ * Retrieve the #CsrVehicleManager type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_VEHICLE_MANAGER csr_vehicle_manager_get_type ()
 G_DECLARE_FINAL_TYPE (CsrVehicleManager, csr_vehicle_manager, CSR,
                       VEHICLE_MANAGER, GObject)
diff --git a/libcroesor/vehicle-service.c b/libcroesor/vehicle-service.c
index c7deeee1b574284d1255fdc6771665dedcbe0942..fe909660d14030d56126bf4e0cb04c8f7e494928 100644
--- a/libcroesor/vehicle-service.c
+++ b/libcroesor/vehicle-service.c
@@ -26,6 +26,15 @@
 #include "librhosydd/vehicle-interface-generated.c"
 #include "librhosydd/vehicle.h"
 
+/**
+ * SECTION:vehicle-service
+ * @short_description: An implementation of a D-Bus interface to expose a collection of vehicles on
+ * the bus.
+ *
+ * See also #CsrVehicleService
+ *
+ * #vehicle-service is available since 0.1.0
+ */
 
 static void csr_vehicle_service_constructed  (GObject *object);
 static void csr_vehicle_service_dispose      (GObject      *object);
diff --git a/libcroesor/vehicle-service.h b/libcroesor/vehicle-service.h
index 273696cc7426418c0bce68d53d2eca5ab4f98342..b51205892024c46ba1408435fd896cf9277bc8d9 100644
--- a/libcroesor/vehicle-service.h
+++ b/libcroesor/vehicle-service.h
@@ -21,6 +21,13 @@
 
 G_BEGIN_DECLS
 
+/**
+ * CSR_TYPE_VEHICLE_SERVICE:
+ *
+ * Retrieve the #CsrVehicleService type.
+ *
+ * Since: 0.2.0
+ */
 #define CSR_TYPE_VEHICLE_SERVICE csr_vehicle_service_get_type ()
 G_DECLARE_FINAL_TYPE (CsrVehicleService, csr_vehicle_service, CSR, VEHICLE_SERVICE,
                       GObject)
diff --git a/libcroesor/version.h.in b/libcroesor/version.h.in
index e04f5e707c8b11a3e7f2a84a36f278d2e22ec9ea..28b972b4a954f64507570de6ad38ccb6cc1d2142 100644
--- a/libcroesor/version.h.in
+++ b/libcroesor/version.h.in
@@ -8,6 +8,15 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+/**
+ * SECTION:version
+ * @short_description: Macros to manage the version
+ *
+ * Provides different macros to retrieve and check libcroesor version.
+ *
+ * #version is available since 0.1.0
+ */
+
 #ifndef CSR_VERSION_H
 #define CSR_VERSION_H