The unload process reverses what was done during the load process. Autoloaded modules can be auto-unloaded or demand unloaded. Demand loaded modules, however, can be unloaded only using a demand-unload. If you try to execute a demand-unload when a module is being used, the demand-unload will fail. Instead of being unloaded immediately, the module will be unloaded using auto-unload the next time auto-unloading is done on the system.