The File object is a simple 2-output Workflow Utility. The top "File exists" output will be followed if the passed-in file exists, and the bottom "else" output will be followed if the file doesn't exist.
If the file exists, optionally set a variable to the UTI of the file. By default, this variable is set as fileuti. It is recommended that you set unique variable names if you are using multiple File utility objects.
When a File list is passed into the File Utility object, the "File exists" output will only be followed if all files exist. The UTIs output will be comma separated.