In CMS 2002, templates are split into two parts. All the information about a template is stored in an object called a template gallery item (TGI), and the physical code is stored in an ASPX file (and the matching code-behind). In this section, we'll examine the TGI and how to change its properties, including adding placeholders and custom properties.
What Are They?
A TGI, in essence, is a list of all the properties or metadata for a given template. It contains all the information that CMS knows about a template, including the definition for all placeholders in the template, the custom properties, and the location of the physical template file. Further, when your content contributors choose a template, they're actually looking at the list of TGIs that exist within the gallery they've chosen.