In addition to importing HTML and text files you can also use a command that enables you to merge external HTML files into existing topics at publish time with the HTML Code Object tool. The files can be local or read from a location on the Internet with a URL. This can be very useful if you have material that changes frequently. You can maintain it in an external HTML file and automatically merge the latest version into your project when you publish.
This only works in HTML-based output formats. Merged HTML files are not included in PDF, printed manuals and MS Word DOCX output.