13.6 Comments
A comment starts with two adjacent hyphens and extends up to the end of the line.
Syntax
comment ::= --{non_end_of_line_character}
A comment may appear on any line of a program.
Semantics
The presence or absence of comments has no influence on whether a program is legal or illegal. Furthermore, comments do not influence the meaning of a program; their sole purpose is the enlightenment of the human reader.
Examples
--  this is a comment

end--  processing of Line is complete

--  a long comment may be split onto
--  two or more consecutive lines

----------------  the first two hyphens start the comment