Like place, period is commonly found as an element in the subjects of books. This is not limited to the discipline of history, but occurs in the great majority of subjects. Period can be expressed as specific periods, actual dates, or in broader and more general ideas of time:

Since period is such a common element of compound subjects you might expect that time subdivisions would be provided for in the same way as geographic subdivisions, but that is not the case. There is a very limited selection of periods available within the free-floating subdivisions, and time is usually expressed through various kinds of main heading. This means that you cannot create headings with dates, as you created headings with places, but are restricted to those dates and times that are specified. It is rather difficult to predict how any individual heading will be dealt with, but it is possible to discern some general approaches.

Free-floating subdivisions for history

There is some provision for very basic historical arrangement of a topic, using the subdivision ‘–History’, which is further qualified by century divisions for the 16th, 17th, 18th, 19th, 20th and 21st centuries. LCSH uses numbers here in preference to words and the subdivisions are written as, for example:

The ‘History’ part must always be included, and these subdivisions may be applied to any topic:

–To 1500 is available for history before the modern period, but there is no means of expressing the medieval period more precisely using the free-floating subdivisions.