Abbreviations plural forms

Rule 5 Do not add a plural s to make an abbreviated unit plural (unless you are using the plural form of spelled-out units, e.g., milligrams). 

In older usage, particularly for monoterpenes, nor denotes loss of all methyl groups attached to a ring system, e.g., norborane, norpinane. The plural form should be bisnor when two carbon atoms are lost from the same site and dinar where they are lost from different sites, bnt in practice the terms are nsed interchangeably. o-. Abbreviation of ortho-. 

The plural forms of those default abbreviations are also used in the CA files. But the plural form is not printed as such in the list, see e.g. concentration ... 

Rule 10 Form the plural of multiple-letter, all-capital abbreviations and abbreviations ending in a capital letter by adding a lowercase s only. Do not put an apostrophe before the s do not add an s to units of measure ... 

To avoid ambiguity or poor appearance, add an apostrophe and a lowercase s to form the plurals of lowercase abbreviations, single-capital-letter abbreviations, abbreviations ending in a subscript or superscript, and abbreviations ending in an italic letter. 

The distinction between uppercase and lowercase letters should be followed, even if the symbol appears in applications where the other lettering is in uppercase style. Unit abbreviations have the same form for both singular and plural, and they are not followed by a period (except in the case of inches). 

Forming the plural of all-capital abbreviations. Add a lowercase s only, with no apostrophe. 

---