diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 591c03028..cdcc8b877 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -3956,6 +3956,45 @@ system and gives an overview of their function and contents.
       material for Wic is located in the
       ":doc:`/ref-manual/kickstart`" chapter.
 
+   :term:`IMAGE_EXTRA_PARTITION_FILES`
+      A space-separated list of files installed into the extra partition
+      when preparing an image using the Wic tool with the
+      ``extra_partition`` source plugin. By default,
+      the files are
+      installed under the same name as the source files. To change the
+      installed name, separate it from the original name with a semi-colon
+      (;). Source files need to be located in
+      :term:`DEPLOY_DIR_IMAGE`. Here is a
+      example::
+
+         IMAGE_EXTRA_PARTITION_FILES = "foo bar.conf;bar"
+
+      Alternatively, source files can be picked up using a glob pattern. In
+      this case, the destination file must have the same name as the base
+      name of the source file path. To install files into a directory
+      within the target location, pass its name after a semi-colon (;).
+      Here are two examples::
+
+         IMAGE_EXTRA_PARTITION_FILES = "foo/*"
+         IMAGE_EXTRA_PARTITION_FILES = "foo/*;bar/"
+
+      The first example
+      installs all files from ``${DEPLOY_DIR_IMAGE}/foo``
+      into the root of the target partition. The second example installs
+      the same files into a ``bar`` directory within the target partition.
+
+      You can also specify the target by label, UUID or partname if multiple
+      extra partitions coexist. Here are two examples::
+
+         IMAGE_EXTRA_PARTITION_FILES_label-config = "foo/*"
+         IMAGE_EXTRA_PARTITION_FILES_uuid-e7d0824e-cda3-4bed-9f54-9ef5312d105d = "foo/*;bar/"
+
+      You can find information on how to use the Wic tool in the
+      ":ref:`dev-manual/wic:creating partitioned images using wic`"
+      section of the Yocto Project Development Tasks Manual. Reference
+      material for Wic is located in the
+      ":doc:`/ref-manual/kickstart`" chapter.
+
    :term:`IMAGE_FEATURES`
       The primary list of features to include in an image. Typically, you
       configure this variable in an image recipe. Although you can use this