(a) The year of initial applicability of a section is indicated by its section number. The two digits following the hyphen designate the first model year for which a section is effective. A section remains effective until superseded.
Example: Section 86.411-78 applies to 1978 and subsequent model years until it is superseded. If a Sec. 86.411-81 is promulgated it would take effect beginning with 1981; Sec. 86.411-78 would apply to years 1978 through 1980.
(b) A reference to a section without a year designation implies the appropriate model year.
Example: When considering 1979 vehicles a reference to Sec. 86.411 implies Sec. 86.411-79. However if no Sec. 86.411-79 has been promulgated then Sec. 86.411-78 is implied; See paragraph (a) of this section.