+> **NOTE**: You doesn't need to specify an **INSTALL** command for these
+> targets. This is already handle by template and will be installed in the
+> following path : **${CMAKE_INSTALL_PREFIX}/${PROJECT_NAME}**
+
+> **NOTE**: if you want to set and use `rpath` with your target you should use
+> and set the target property `INSTALL_RPATH`.
+
+## Add external 3rd party library
+
+### Build, link and ship external library with the project
+
+You could need to include an external library that isn't shipped in the
+platform. Then you have to bundle the required library in the `lib` widget
+directory.
+
+Templates includes some facilities to help you to do so. Classic way to do so
+is to declare as many CMake ExternalProject as library you need.
+
+An ExternalProject is a special CMake module that let you define how to:
+download, update, patch, configure, build and install an external project. It
+doesn't have to be a CMake project and custom step could be added for special
+needs using ExternalProject step. More informations on CMake [ExternalProject
+documentation site](https://cmake.org/cmake/help/v3.5/module/ExternalProject.html?highlight=externalproject).
+
+Example to include `mxml` library for [unicens2-binding](https://github.com/iotbzh/unicens2-binding)
+project:
+
+```cmake
+set(MXML external-mxml)
+set(MXML_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/mxml)
+ExternalProject_Add(${MXML}
+ GIT_REPOSITORY https://github.com/michaelrsweet/mxml.git
+ GIT_TAG release-2.10
+ SOURCE_DIR ${MXML_SOURCE_DIR}
+ CONFIGURE_COMMAND ./configure --build x86_64 --host aarch64
+ BUILD_COMMAND make libmxml.so.1.5
+ BUILD_IN_SOURCE 1
+ INSTALL_COMMAND ""
+)
+
+PROJECT_TARGET_ADD(mxml)
+
+add_library(${TARGET_NAME} SHARED IMPORTED GLOBAL)
+
+SET_TARGET_PROPERTIES(${TARGET_NAME} PROPERTIES
+ LABELS LIBRARY
+ IMPORTED_LOCATION ${MXML_SOURCE_DIR}/libmxml.so.1
+ INTERFACE_INCLUDE_DIRECTORIES ${MXML_SOURCE_DIR}
+)
+
+add_dependencies(${TARGET_NAME} ${MXML})
+```
+
+Here we define an external project that drive the build of the library then we
+define new CMake target of type **IMPORTED**. Meaning that this target hasn't
+been built using CMake but is available at the location defined in the target
+property *IMPORTED_LOCATION*.
+
+You could want to build the library as *SHARED* or *STATIC* depending on your needs
+and goals. Then you only have to modify the external project configure step and change
+filename used by **IMPORTED** library target defined after external project.
+
+Then target *LABELS* property is set to **LIBRARY** to ship it in the widget.
+
+Unicens project also need some header from this library, so we use the target
+property *INTERFACE_INCLUDE_DIRECTORIES*. Setting that when another target link
+to that imported target, it can access to the include directories.