: This code indicates that the image is for Autonomous Mode . k9w7 : Autonomous (Standalone) IOS. k9w8 : Full Lightweight (Controller-based) IOS. rcvk9w8 : Lightweight recovery image.
Check that your AP is a Wave 2 AP (like 1800/2800/3800) – they use different images. Ap3g2-k9w7-tar.153-3.jf15.tar
: Indicates the image includes strong cryptographic features (standard for nearly all Cisco IOS images). : This code indicates that the image is for Autonomous Mode