You can simulate how the function works by loading the package.
The result is a string that can be used as a URL referring to the MSP servlet, which can be used to retrieve the data from the store.
A third argument to MSPURLStore
sets a filename in the URL. There are several uses for this functionality, such as choosing a helper application for the client. Note that no actual file with this name is created. The name is just placed in the URL.