Almost all sections in the Tag Library have Introductions. To find the introduction to a section, click on the name of the section rather than the arrow before the section name. The subsections will open up, but if there is an Introduction it will fill the main panel. At one of the JATS Standing Committee meetings it was revealed that the majority of members had no idea the introductions were there, or how to find them, why they sometimes suddenly appeared, or why you would want to find them.

Figure 26. Introduction to the Elements Pages