Q. Hello. A term you used in your hyphenation table is slightly incorrect, I believe. You call the units of measurement (m, kg, ft.) “abbreviations.” (I assume that things like MB and GHz also fall into this category?) According to Merriam-Webster, an abbreviation is “a shortened form of a written word or phrase used in place of the whole word or phrase. ‘Amt’ is an abbreviation for ‘amount.’ ‘USA’ is an abbreviation of ‘United States of America.’” That has nothing to do with the examples in the table.
A. You are right. However, in CMOS the umbrella term abbreviation is used for acronyms, initialisms, and contractions, as well as for shortened (abbreviated) forms (ibid., vol., prof., etc.), except where greater specificity is required. This is stated more fully at 10.2. I’m sorry if it caused you confusion or inconvenience.