Research on spatial relationrepresentation mainly includes spatial topological relation, spatial cardinal direction relation and spatial distance relation.
对空间关系表示的研究主要包括空间拓扑关系、空间方向关系、空间距离关系三大类空间关系表示的研究。
2
The URI points to a resource, or a representation of a resource, while the relation describes the type or kind of the link.
URI指向资源或者资源的表示，而关系则描述了链接的类型或种类。
3
The relation type is defined by the rel attribute; for example, the value alternate signifies that the link provides an alternate representation of the resource described by the entry element.