This concept defines the model for a functor class used to perform strict comparison between two values of a spatial container, over a single dimension.

The functor shall return a boolean value equal true if the first value is strictly lower than the second value over that dimension.

The models of trivial comparison shall publicly provide the following interface:

	Signature/Typedef	Description
Legend	`T`	A model of Trivial Comparison
Legend	`V`	The key used a spatial container.
Require	`bool T::operator()(spatial::dimension_type x, const V& a, const V&b) const`	Returns true if `a < b` over dimension `d`.

Models of this concept are required for comparison functors in spatial::point_multiset, spatial::idle_point_multiset and other point containers. However, this model is not suitable for Comparison functors in spatial::box_multiset, spatial::box_multimap, and other box containers. For these container, look at Generalized Comparison.