-# A directory where output file(s) will be stored. If does not exist, it will be created. If not specified, current directory is used.
+# A directory where output file(s) will be stored. If does not exist, it will be created. If not specified, current directory is used. One can prefix the directory name with a string indicting file transport protocols (as supported by ROOT). In addition, some file transport protocols are selected by name signatures. At present the following methods are available:
+#
+# o) if file name begins with rfio:, shift:, castor:, hpss:, /shift, /castor, /hpss => rfio (remote file i/o) protocol (requires rfiod on server side)
+# o) if file name begins with root:, roots: => root and secure root protocol (requires rootd on server side)
+# o) if file name begins with http: => HTTP protocol (requires modified apache server on server side)