The value you assign to the 'size' parameter should be the radius of the circle in pixels. The 'mouseover' and 'mouseoff' values specify the colour of the circle while the mouse is over or off the marker respectively. These colours must be set if the 'size' parameter is set. PlotUK allows much more flexibility than this. If you wish, you may override this setting and use a different image for any location.
Every location can have an associated hyperlinks.
Note that the name you wish to associate with a location must be enclosed within double quotes, unless it is a single word with no spaces. The supplied image is centred around this location. Specified the radius of the marker in pixels. By default, this 5 pixels. The path to the image is relative to the location of the definitions file.