Emacs has
csv-comment-start is a variable defined in ‘csv-mode.el’.
Its value is "#"
Automatically becomes buffer-local when set.
Documentation:
String that starts a comment line, or nil if no comment syntax.
Such comment lines are ignored by CSV mode commands.
This variable is buffer local; its default value is that of
‘csv-comment-start-default’. It is set by the function
‘csv-set-comment-start’ -- do not set it directly!
Therefore the Text::CSV man page should mention something about comments.
E.g., "Not allowed!"