Books and Printing and Mormons. Part 3.

When a typesetter/printer talks about space between lines in a book the classical term is leading (placing “leads” between lines). Expressed in points it will usually read larger than the font size. A 12/14 system means 12pt font, 14pt leading. In a book, the normal line length is called the measure. This may be expressed numerically. Like 10/1120. This indicates the book is typeset in a 10pt font, 11pt leading, 20 pica measure. A pica is 12 points (yeah, it’s not base ten folks). A pica is indicated by suffix pc, such as 33pc. 10pc = 120pt.
Read more of this post