The Package Declaration ensures that the location of a source file in the file tree is correct. For example, the below Dyvil file has to be located in the directory tree as shown.
If the package declaration is missing or does not match the directory structure, an error is raised by the compiler.
If every class in a project shows such an error, you should check your
sourcedirectory in the Compiler Configuration. Note that the value of this option is the
srcdirectory in the above example.