If the template is used with no parameters it defaults to the American spelling of color
If one parameter is passed it will default to the Commonwealth spelling of colour
{{Chủ_đề_màu_sắc|colour}}
More than one parameter will be ignored. The value passed as the first parameter does not matter (for example it could be "x", "colour" or even "color") so long as it is set to something, then Commonwealth spelling will be used. However to make it self documenting it is recommended that "colour" be used as the parameter value.