Very cool! I haven't looked at the composition yet, but I believe the normal path to the enclosing (parent) folder is '../myFile' (without the quotes)
However, running some tests on a sample app here shows that path doesn't seem to work, instead only 'myFile' is working, which writes to the Desktop folder, regardless of how deeply nested my test app is. You can always write in the whole path, with ~ being the user directory. for example '~/Desktop/mySubFolder/myOtherFolder/'