Abstract: An authoring system for assigning geo-spatial position to sensory-effect data is disclosed. The sensory-effect data can include one or more of the group of alpha numeric data, image data, sound data, smell data, temperature data, humidity data, wind data, pressure date and light data. The alphanumeric data may comprise computer readable code for, in use, instructing the system to control presentation of the sound, image, smell, humidity, wind, pressure, or light data to an exposee. The authoring system may comprise a user interface on which the geo-space is represented, the interface being arranged in a manner such as to enable, in use, a user to assign the geo-spatial position to the data by placing and manipulating markers on the interface. The authoring system preferably comprises means for defining relationships between markers.