# Macro identifier delimiter char (`'%'` by default).
	#
	# To use a different delimiter you can subclasse `TemplateString` and defined the `marker`.
	#
	#     class DollarTemplate
	#         super TemplateString
	#         redef var marker = '$'
	#     end
	#     var tpl = new DollarTemplate("Hello $NAME$!")
	#     tpl.replace("NAME", "Dave")
	#     assert tpl.write_to_string == "Hello Dave!"
	protected var marker = '%'