The Project Files > Baggage Files section in the Project Explorer enables you to add a collection of small, frequently-used files to your project. The entries in the Baggage Files section are not links or references, they become a physical part of your project.
These files are stored together with your project files and they are always accessible, even if you delete the original source files. If you use the single-file .hmxz format your baggage files are stored inside your project file. In the uncompressed .hmxp XML format (Professional and Server versions only) they are stored in the Baggage folder inside your project folder.
Using Baggage Files