Open the referenced file (e.g., filename.html ), copy its entire code, and paste it directly over the include tag in your main SHTML file.

http:// /view/viewer_index.shtml

Mastering Server-Side Includes: How to View SHTML Files and Test Them Locally

Include common headers, footers, or navigation menus across multiple pages without duplicating code.

While SHTML still works and appears on many legacy systems, consider whether newer alternatives might be better for your projects:

If you open a web page and literally see printed as text on your screen,