The PROD (PRODuction) tag is a bit value that denotes if the image/ticket signature is for production devices or not. It is present in the SHSH certificate img3 and APTicket. When set to
true, the image is designated to be installed onto production and development devices. When the tag value is
false, the image/ticket is only explicitly accepted on internal devices. This is enforced through iBoot's
do_load_image(void); routine. The routine skips the PROD tag check if the device's fuse value is
This is to prevent production devices from running non-production code.