-# Each nonempty line of the input file is either an option specification
-# or # a tree specification. An option specification (described later)
-# begins with an @ character. Other lines specify tree nodes.
+# Each nonempty line of the input file is either a comment, an option
+# specification or a tree specification. Each line is distinguished by
+# its first character. A # character introduces a comment, an @ character
+# introduces an option specification (described later), and all other
+# nonempty lines are tree nodes.