30 CFR § 7.6 Approval marking and distribution record.
(a) Each approved product shall have an approval marking, as
specified in the appropriate subpart of this part.
(b) For an extension of approval, the extension number shall be added
to the original approval number on the approval marking.
(c) Applicants shall maintain records of the initial sale of each
unit having an approval marking. The record retention period shall be at
least the expected shelf life and service life of the product.