Value is a list of switches to be used by the cleaning application.
Index is a language names. Value is the list of extensions for file names derived from object file names that need to be cleaned in the object directory of the project.
Index is a language names. Value is the list of extensions for file names derived from source file names that need to be cleaned in the object directory of the project.
Value is a list of file names expressed as regular expressions that are to be deleted by gprclean in the object directory of the project.
Value is list of file names expressed as regular expressions that are to be deleted by gprclean in the exec directory of the main project.