The script:
- may call ScriptCookie() during script initialization and save the resulting cookie string
- may use the cookie string to register to core pcb-rnd infrastructure that requires cookie, such as CreateMenu
- can depend on pcb-rnd to call any unregistering associated with this specific cookie atomatically after script unload (preunload).
The function can not be called outside of script initialization. The cookie
string can be used any time between script load and script unload.