--- a/Sphinx/source/faq/features.rst	Sun Apr 16 13:50:18 2023 +0200
+++ b/Sphinx/source/faq/features.rst	Sun Apr 16 16:55:46 2023 +0200
@@ -433,9 +433,9 @@
 Check out the `OpenAPI reference <https://api.orthanc-server.com/>`__
 of the REST API of Orthanc for more information.
 
-**Warning:** The database index back-end must support revisions. As of
-writing, only the **PostgreSQL plugins** in versions above 4.0 and the
-**ODBC plugins** implement support for revisions.
+**Warning:** The database index back-end must implement support for
+revisions. As of writing, only the **PostgreSQL plugins** in versions
+above 4.0 and the **ODBC plugins** implement support for revisions.
 
 
 Synchronous vs. asynchronous C-MOVE SCP
@@ -469,3 +469,82 @@
 C-MOVE client and a hospital-wide PACS. This can be interesting to
 introduce compatibility with specialized image processing
 applications.
+
+
+.. _labels:
+
+Labels
+------
+
+.. highlight:: text
+
+Orthanc 1.12.0 introduces the concept of **labels**. A label is a
+string that can be attached to any DICOM resource (i.e. patients,
+studies, series, or instances). In contrast with :ref:`metadata
+<metadata>`, labels are not associated with a value, however labels
+are **indexed in the Orthanc database** for efficient lookups.
+
+Labels can notably be used as the building block to implement
+**multi-tenancy**, which means that a single database could be shared
+between different tenants that are distinguished by different labels.
+This idea is illustrated by the :ref:`multitenant DICOM server
+<multitenant-dicom>` sample plugin. A similar approach could be used
+to implement Web interfaces that restrict the resources that are
+accessible to some users by assigning labels to users. Labels are also
+useful in **machine learning** (or deep learning) workflows to
+separate DICOM resources belonging to the training set or to the
+testing set.
+
+The labels attached to one given DICOM resource can be read through
+the REST API::
+
+  $ curl http://localhost:8042/instances/19816330-cb02e1cf-df3a8fe8-bf510623-ccefe9f5/labels
+  $ curl http://localhost:8042/series/3774320f-ccda46d8-69ee8641-9e791cbf-3ecbbcc6/labels
+  $ curl http://localhost:8042/studies/66c8e41e-ac3a9029-0b85e42a-8195ee0a-92c2e62e/labels
+  $ curl http://localhost:8042/patients/ef9d77db-eb3b2bef-9b31fd3e-bf42ae46-dbdb0cc3/labels
+
+A label can be added to one DICOM resource using the PUT HTTP method,
+and can be removed using the DELETE HTTP method::
+
+  $ curl http://localhost:8042/studies/66c8e41e-ac3a9029-0b85e42a-8195ee0a-92c2e62e/labels
+  []
+  $ curl http://localhost:8042/studies/66c8e41e-ac3a9029-0b85e42a-8195ee0a-92c2e62e/labels/hello -X PUT -d ''
+  $ curl http://localhost:8042/studies/66c8e41e-ac3a9029-0b85e42a-8195ee0a-92c2e62e/labels
+  [ "hello" ]
+  $ curl http://localhost:8042/studies/66c8e41e-ac3a9029-0b85e42a-8195ee0a-92c2e62e/labels/hello -X DELETE
+  $ curl http://localhost:8042/studies/66c8e41e-ac3a9029-0b85e42a-8195ee0a-92c2e62e/labels
+  []
+  
+The built-in :ref:`Orthanc Explorer <orthanc-explorer>` Web interface
+can be used to display, add, and remove labels.
+
+Once labels are set, the ``/tools/find`` :ref:`route of the REST API
+<rest-find>` of Orthanc can be used to efficiently look for the DICOM
+resources that are associated with given labels. This is done by
+providing the set of labels of interest in the ``Labels`` field, as
+illustrated in the following request::
+
+  $ curl --request POST --url http://localhost:8042/tools/find \
+    --data '{
+              "Level" : "Study",
+              "Labels" : [ "hello" ],
+              "LabelsConstraint" : "All",
+              "Query" : { }
+            }'
+
+The ``LabelsConstraint`` field can be used to control the request over
+the labels. Its value can be ``All`` (to return the resources that are
+associated with all the labels provided in the ``Labels`` field at
+once), ``Any`` (to return the resources that are associated with at
+least one of the labels provided in the ``Labels`` field), or ``None``
+(to return the resources that are associated with none of the labels
+provided in the ``Labels`` field). If not provided,
+``LabelsConstraint`` defaults to ``All``. Note that in the if there is
+only one label in the ``Labels`` field, both ``Any`` and ``All`` have
+the same behavior.
+
+            
+**Warning:** The database index back-end must implement support for
+labels. As of writing, only the **PostgreSQL plugins** in versions
+above 5.0 and the **MySQL plugins** in version above 5.0 implement
+support for labels.

--- a/Sphinx/source/plugins.rst	Sun Apr 16 13:50:18 2023 +0200
+++ b/Sphinx/source/plugins.rst	Sun Apr 16 16:55:46 2023 +0200
@@ -86,6 +86,7 @@
    plugins/indexer.rst
    plugins/neuro.rst
    plugins/volview.rst
+   plugins/multitenant-dicom.rst
 
 .. _plugins-contributed:
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Sphinx/source/plugins/multitenant-dicom.rst	Sun Apr 16 16:55:46 2023 +0200
@@ -0,0 +1,77 @@
+.. _multitenant-dicom:
+
+
+Sample multitenant DICOM server
+===============================
+
+.. contents::
+
+This **official** plugin by the `ICTEAM institute of UCLouvain
+<https://uclouvain.be/en/research-institutes/icteam>`__ can be used to
+turn Orthanc into a **multitenant DICOM** server using :ref:`labels
+<labels>`. More precisely, the same Orthanc database can be accessed
+from different DICOM servers, that each provides a different view
+depending on the presence of labels. This plugin available is part of
+the `official source distribution
+<https://hg.orthanc-server.com/orthanc/file/default/OrthancServer/Plugins/Samples/MultitenantDicom>`__
+of Orthanc, starting with Orthanc 1.12.0.
+
+This plugin starts additional DICOM servers, in complement to the main
+DICOM server of Orthanc that provides full access to the Orthanc
+database. These additional DICOM servers support the C-Find, C-Move,
+and C-Store commands, and share most of their configuration with the
+main DICOM server of Orthanc. They are however distinguished from the
+latter by using a **different AET** and a **different TCP
+port**. Furthermore, each of those additional DICOM servers are
+associated with a **set of labels** that restricts which DICOM
+resources stored in Orthanc are accessible through this additional
+DICOM server.
+
+.. highlight:: json
+
+Here is a sample :ref:`configuration file <configuration>` to use this
+plugin::
+  
+  {
+    "Plugins" : [ "." ],
+    "DicomModalities" : {
+      "sample" : [ "STORESCP", "127.0.0.1", 2000 ]
+    },
+    "MultitenantDicom" : {
+      "Servers" : [
+        {
+          "AET" : "HELLO",
+          "Port" : 4343,
+          "Labels" : [ "hello" ],
+          "LabelsConstraint" : "All",
+          "LabelsStoreLevels" : [ "Patient", "Study", "Series", "Instance" ]
+        }
+      ]
+    }
+  }
+
+This configuration will start an additional DICOM server with AET
+``HELLO`` listening on the 4343 port. This DICOM server will work as
+follows:
+
+* DICOM C-Find and C-Move requests are restricted to the DICOM
+  resources that are assigned with the ``hello`` label.
+
+  * Note that the labels are checked by query/retrieve level: For
+    instance, if ``QueryRetrieveLevel (0008, 0052)`` equals ``STUDY``,
+    the plugin will only report the studies that are associated with
+    the ``hello`` label.
+
+  * The ``LabelsConstraint`` specifies the type of constraint on the
+    labels. Its value can be ``All`` (default), ``Any``, or ``None``,
+    which corresponds to the values accepted by the ``/tools/find``
+    :ref:`route in the REST API <labels>` of Orthanc. Note that in the
+    sample configuration above, because there is only one label in the
+    ``Labels`` field, both ``Any`` and ``All`` have the same behavior.
+  
+* Any DICOM resource that is received through DICOM C-Store requests
+  issued to this additional DICOM server, is automatically associated
+  with all the labels provided in the ``Labels`` field. The
+  configuration option ``LabelsStoreLevels`` can be used to restrict
+  the levels to which the labels are applied (it defaults to the three
+  study, series, and instances levels).

--- a/Sphinx/source/users/rest.rst	Sun Apr 16 13:50:18 2023 +0200
+++ b/Sphinx/source/users/rest.rst	Sun Apr 16 16:55:46 2023 +0200
@@ -1090,8 +1090,7 @@
 
   $ curl -X POST http://localhost:8042/tools/find -d '{"Level":"Series","Query":{"DeviceSerialNumber":"123\\abc"},"Expand":true}'
 
-  
-  
+ 
 Additional Options
 ^^^^^^^^^^^^^^^^^^
 .. highlight:: json
@@ -1144,6 +1143,11 @@
   ]
 
 
+**Important:** Starting with Orthanc 1.12.0, this route in the REST
+API also provide the ``Labels`` and ``LabelsConstraint`` options to
+bring support for :ref:`labels <labels>`.
+
+
 .. _changes:
 
 Tracking changes