A Line beginning with a character '#' is regarded as a comment line.
The character '#' must be put at the first column.
(Indentation of comment lines are not allowed.)
The first line of the whole data should be a comment line as
``##G4.PRIM-FORMAT-2.4''.
We call this line the ``header-comment line'' below.
Blank lines are acceptable except for the very first line of the whole date.