ScriptX provides a unique id that is persistent to the registry and therefore not subject to issues that can affect client-side cookies.
The unique id is a generated GUID, not the machine MAC address or processor identifier. On creation it is persisted to the registry and can be passed back to server side code for retrieval of stored information.
It should not be assumed that the value is secure or tamper proof.
The id may be requested as unique for the logged on user, or for the machine. The latter case being that the same id is returned for all users of the PC. The creation of an id for the machine requires administrator priviledges so when Internet Explorer protected mode is enabled, a UAC elevation prompt may occur.
Due to the interactions that may occur, a unique identifier should only be requested when the document has fully loaded.
The id will persist across re-installs, upgrades etc of ScriptX, but will be lost if, say, a previous version of the registry prior to creation of the id is restored.