How should I classify a book about a particular century in a country's history--for example, 19th-century Portugal--when DDC numbers are provided for several periods within that century and there is no explanatory instruction?

Look for the best fit between the years of the century and the years of the historical periods of that country's history. We normally observe the following two guidelines. When one period covers 51 or more years of a century (defining a century as the years ending in 00 to 99), we use that period, because it covers the majority of the century. For example, 946.9036 encompasses 1847-1910 in Portuguese history. Because this period includes 53 years of the 19th century, we use 946.9036 for 19th-century Portugal. If a period covers the first 50 years of a century, we use that period, according to the first of two rule. For example, 946.9032 covers 1640-1750 in Portugal, and 946.9033 covers 1750-1807. Eighteenth-century Portugal, therefore, is classified in 946.9032.

Additional difficulties arise when a century is divided among three or more periods. For example, the 20th century in Albanian history is divided among four period subdivisions. The first 12 years of the century are included in 949.6501; the subdivision for 1912-1946 (949.6502) encompasses the following 34 years; the next 46 years of the century are covered in 949.6503, which has the caption "1946-1992"; and 949.6504 is for 1992 and after. We realize that users require more guidance in such instances, and we plan to add notes indicating where the centuries are to be classed in all doubtful cases to Edition 22, which will be published in 2003. We will also add selected notes to future releases of WebDewey. In the Albanian history example, it is likely that we will designate 949.6503 to be used for 20th-century Albania, because it covers nearly half the century.

Last revised: 05 September 2003