maint: This is the name of the agency or organization that maintains the system.
formed: This is the date of the system's formation. (Alternate parameter: formed)
length_mi: or length_km: This is the length of the system. length_ref is used for the reference for this piece of information, and the template converts the given length into both systems of measurement.
notes: Additional information about the highway system.
country, state, or province: just as with {{infobox road}}, but used to display the appropriate links at the bottom of the infobox.
type: Optional. Customizes the links displayed for some jurisditions based on roadway type.
county: Optional. Customized the links displayed for some states based on county, for county roads.
field1–6 Optional. Allows up to six additional types of highways to be added to the list.
label1–6 Required only if using field1–6. Adds a label for the field1–6 lines.