When I tried to learn the meaning of each tag in package.xml, I understood the meaning of <build_depend> and <exec_depend>.

However, after reading the explanation in the ROS Wiki

Build Export Dependencies specify which packages are needed to build libraries against this package. This is the case when you transitively include their headers in public headers in this package (especially when these packages are declared as (CATKIN)DEPENDS in catkinpackage() in CMake).

, I was still confused about the meaning of <build_export_depend>.

Even for some packages, <build_export_depend> is not required.

Can anyone give a more intuitive and easier-to-understand explanation about <build_export_depend>?

Thanks!