Section 7.29 - Approval marking(a) Approved brattice cloth shall be legibly and permanently marked with the assigned MSHA approval number at intervals not exceeding ten feet. If the nature of the material or method of processing makes such marking impractical, permanent paint or ink may be used to mark the edge with an MSHA-assigned color code.(b) Approved ventilation tubing shall be legibly and permanently marked on each section with the assigned MSHA approval number.(c) An approved product shall be marketed only under a brand or trade name that has been furnished to MSHA.