The Class Number is a combination of letters and numbers. It's separated from the cutter number by a decimal point. The class number to the right indicates that this periodical (library code PERIODICAL) belongs to the subject area Modern European Languages.
Class Numbers usually consist of 1 or 2 letters followed by numbers from 1-9999. The number could contain a decimal point (not to be confused with the decimal separating class and cutter numbers). Here are some examples in call number order :
The first unit is the Class Letter. You first put the book in alphabetical order by this letter. Then, after letter order, you put the books in numerical order. For instance, once you have the Ps together, you can put them in order P, PA, PB, PC. Then you put in order by number from P1 - P9999, PA1 - PA9999, etc.
NOTE: There is only one class number without letters (older law books), and two areas (DKJ and KBA-KXZ) that have 3 letters. Some parts of the K class have letters with no numbers.