Let’s examine each of the properties defined in the book item descriptor. The author and title properties are simply strings, with one-to-one relationships between books and authors and books and titles. More complex relationships are possible, of course.
The book’s cover illustration is a special case. Since it is an image and isn’t subject to change, we’ve decided to maintain it on the file system, outside the repository’s database. The book item descriptor therefore defines a property named bookcover_image. The property is not defined inside a <table> tag. This indicates that the property is transient and not maintained in the database. To indicate that this property is a file type, the bookcover_image uses the following attribute:
property-type="atg.repository.FilePropertyDescriptor"
As described in the Storing Content on a File System section, this property type indicates that the repository should use the property’s path name and convert it to a java.io.File object.
