中文说明：
基于位置的协作，人与人或人与地的时空关系的变化是协作的关键语境。因此，基于位置的协同环境应该支持时空事件sub/pub服务。时空事件订阅的关键问题是如何指定不同的时空事件。
English Description：
The key context of collaboration is the change in spatiotemporal relationships between people or people based on location. Therefore, a location-based collaborative environment should support spatiotemporal event sub/pub services. The key issue in subscribing to spatiotemporal events is how to specify different spatiotemporal events