Because LCSH is such a complicated system, we will start by looking at how you can apply the headings exactly as they are published in the lists, either printed or online. In lots of cases the subjects of documents can be very well expressed simply by using one or more headings, without any further effort. In later chapters we will consider how to add subdivisions to these main headings, and how to create new headings where this is permitted. If you have access to Cataloguers’ Desktop, it would useful to read the Introduction to the Subject Headings Manual at this stage. [Note: I have used the expression ‘main headings’ to indicate the headings as they occur in the published list of headings, and to differentiate these from subdivisions, and combinations of headings and subdivisions.]

Content analysis and LCSH

It is important that you go through the process of analysing the content of the document and establishing its subject before you begin to decide which headings to use. Remember that content analysis has two main objectives: to make a concise summary of the document's subject; and to identify any topics that users may be trying to retrieve. In the first case, the concept analysis should state the general subject of the document, which may be very broad (economic theory, the postal service, archaeology), or quite specific and complicated in nature (American films of the 1930s, manuscript illumination in Medieval Germany, laser excision of epithelial tumours). Your objective then is to try and find a heading, or set of headings, that will represent all the significant parts of the document's subject.

Analytical cataloguing

Most conventional library cataloguing and indexing stops at that point. The document is located physically alongside other documents with similar and related topics, and it has sufficient data in the subject field of the catalogue record to retrieve it according to its content. In other environments the practice of analytical indexing or cataloguing aims to provide subject information about the detailed content of a document; individual chapters or sections are indexed, and there is much more information about very precise topics.