![rubicode rcdefaultapp rubicode rcdefaultapp](https://images.sftcdn.net/images/t_app-cover-l,f_auto/p/ea309f98-9b2e-11e6-bb60-00163ec9f5fa/4154649801/rcdefaultapp-screenshot.jpg)
![rubicode rcdefaultapp rubicode rcdefaultapp](https://images.sftcdn.net/images/t_app-cover-l,f_auto/p/ea309f98-9b2e-11e6-bb60-00163ec9f5fa/205801386/rcdefaultapp-screenshot.jpg)
These Finder metadata are moved around in a special storage area associated with every file in the Macintosh Extended (HFS+) volume format, its resource fork. In the case of applications, they have the type APPL, so the Finder knows to start them in the case of a document, the Finder tries to start the application indicated as being the document’s creator. Every file has there two four-character codes giving the file type and its creator.
#Rubicode rcdefaultapp mac os#
On a Classic Mac running Mac OS 9, your double-click is passed to the Finder, which then looks in its hidden database to see what type of object you have tried to open.
![rubicode rcdefaultapp rubicode rcdefaultapp](https://cdn-ak.f.st-hatena.com/images/fotolife/c/cruller/20171018/20171018121836.png)
In the case of an application, it should start up a document should be opened by the default app set to handle that type of document a folder should open and reveal its contents. However when you tap or double-click on the icon representing a file or folder, you expect the computer to know what you want to do. To any computer, even devices that contain computers but present themselves to consumers as smartphones or tablets, files are just discrete storage units, and folders just containers for files. Macs used to be the only computers that did not need filename extensions now they have conformed, but iOS lacks them.