The "(N-SUB)" tag often indicates a version or a specific naming convention used in course downloads or video archives. The ".part" extension suggests this is one segment of a larger series or a compressed archive file (like .part1.rar). Which of these

A draft to promote this specific course or video?

If you are looking for what a typical "Introduction to Adobe InDesign" part covers, it generally includes:

Importing text, applying character/paragraph styles, and managing text frames.