(1) The following is the basis of measurement for the computation of folios in the various sizes of type, when set in a column 13 ems pica wide, and constitutes a folio within the meaning of this part:
(a) 12 lines of 6-point type;
(b) 14 lines of 7-point type;
(c) 16 lines of 8-point type;
(d) 18 lines of 9-point type; or
(e) 20 lines of 10-point type.
(2) A carefully verified actual count shall be made of the folio.