parameter_descriptions and parameter_updates topics

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Dear friends,

I experiment with hector quadrotor simulation in Hydro. Most of the topics like the one for sonar of the altimeter includes additional topics like /sonar_height/parameter_descriptions and /sonar_height/paramater_updates.

What is the use of these topics in every component?

It can be used in order to change the on fly the parameters of the virtual device or something else?

Thanks for the help!