A file type becomes the initial value of the property when opening a file.
The property when opening a file turns into a property which is in agreement with the extension registered by the file type. When there is no property in agreement, the file type with which the extension is "*" is chosen.
It is the list which displays the file type registered.
A file type is registered newly. The initial value of a new item turns into a value of the file type selected now.
The file type selected now is removed.
The file type selected now is 1 up.
The file type selected now is 1 down.
The file type selected now is edited. Details of File Type are displayed.