A path to a file. When setting this type of attribute a file selection dialog is shown instead of a text box. The selected file is entered as the attribute value for that note. If no default value is specified, a File type defaults to an empty string.
The path stored is in POSIX form (forward slash delimited) and is the full local path to the file or folder.
When files from the user's directory are dropped into Tinderbox or into a file attribute, Tinderbox uses the tilde (~) abbreviation to represent the path to the user's directory. This should make it easier to share one Tinderbox document across several machines, each of which share files in common locations (e.g. Dropbox) but which have different user names.
When displayed in a note's displayed attributes table, Find-type attributes show a folder icon before the attribute value. Pressing the icon opens that attribute's stored OS file path (if any) for a file, using the in the default app as determined by Finder, or for a folder it opens Finder.
As for String Data Type.