I want to offer the option to add .indt template documents to a book, with text and object styles and text variables distributed, but excluding pages.

Thus, template documents will be possible to use not only for creating new documents, but also for distributing established styles in a book and even to many books from just one file!

The existing method of importing styles from a regular document within a single book often leads to confusion of style options if the wrong document is selected.

A file from which regular pages will not be imported will be a universal source of styles, for example, for multi-volume publications or magazines.

Alternatively, it is possible to allow only parent template pages to be imported.