
/*!
\ingroup PkgSearchStructuresConcepts
\cgalConcept

Defines the requirements that a
`Sublayer_type` of class `CGAL::Range_tree_d`
or `CGAL::Segment_tree_d` has to fulfill.

First of all, the class has to be derived from the abstract base
class `CGAL::Tree_base` and therefore
has to provide methods
`make_tree`, `window_query`,
`enclosing_query` and
`is_inside`
with the same parameter types as the instantiated class
`Range_tree_d` or `Segment_tree_d`,
respectively.
Furthermore a method `bool is_anchor()` has to be provided. If the `Sublayer_type` class
builds a recursion anchor for class
`Segment_tree_d`, this function is expected to
return `true`, `false` otherwise.

Such a recursion anchor class is provided by the class class.
`CGAL::Tree_anchor<Data, Window>`.

*/

class Sublayer {
public:

}; /* end Sublayer */

