I think tha 1:/ is for rwfs becouse if you look in FW you will see beside 1:/ only few .System folder but after 2:/ you see Garmin folder.

In New Fw is example: 0:/ .System/JCV .... 2:/ Garmin/JCV but on 3490 you have 0:/.System/JCV .... 1:/Garmin/JCV