Info server URL template is used to fetch key/value pairs for the variable substitution in the info panel content template. The specified template typically contains macro place holders that are replaced with the actual data before the request is sent to the server.
$1$ is replaced with the rollover value that triggered the InfoPanelPopup activation.
$2$ is replaced with the sequence number of the current frame in the image set.
$3$ is replaced with the first path element specified in the name of the parent set of the current item. It typically corresponds to the catalog id.
$4$ is replaced with the following element in the path and corresponds to the asset id. The actual info server request syntax is info server dependent and it differs from server to server. For example, the following is a typical Dynamic Media info server request template: