The 20-MW TVA atmospheric fluidized-bed boiler / prepared by Tennessee Valley Authority ; principal investigators, A. Manaker, J. Bass. (OCLC #22758855)

The Library of Congress Classification and Shelflisting Manual Part G 63 describes the process of assigning Cutter numbers in an LC call number.

This work has title as its main entry, so will be cuttered based on the title; since the title starts with the article ‘The’, we’ll base the cutter off of the next word, ’20-MW’, which starts with a numeral.

The manual’s section on Cuttering for numerals says “When Cuttering for Roman or Arabic numerals, use the Cutters .A12 – .A19.” Since this title starts with the numeral ‘2’, I was considering .A12, but the next instruction says:

Because of the infinite range of numbers, choose a Cutter
toward the center of the available span when Cuttering for the first numeral in a class. This will allow room for both smaller and larger numbers. Follow this practice even with relatively low numbers since decimal fractions are filed in numeric order before the number 1.

There were no other titles (or authors) starting with numerals in this part of our shelflist, so I followed the advice and cuttered with .A15:

   TH7140 .A15 1989