Choosing the filetype can be either by typing in the name/hexcode as with the Filer, or by clicking on the filetype from a window showing all the filetypes that have been 'seen' by the Filer up to that point. An example is shown to the left.
Dragging a selection of files and/or directories onto this window, or the iconbar icon, will set the filetype (including files in sub-directories).
The default type is text and the iconbar icon for dType is the file icon with the hex filecode underneath as shown below: