Here’s a technical write-up for the Cisco IOS image :
The VIOS-ADVENTERPRISEK9-M.SPA.159-3 is a specific software image for Cisco's IOS XE software. It is designed for the Cisco 4000 Series Integrated Services Routers (ISRs). The image is a universal image that supports various features and capabilities, making it an ideal choice for enterprises. vios-adventerprisek9-m.spa.159-3