Some googling yielded that the build sheets pull current info for the 3 and 4 digit codes. It could be that at time of manufacture that code meant something else (post below implies OBD reader) but it is currently assigned to Delete Remote Start.
“When Chrysler generates an options list for our TJ Wranglers (or any older vehicle), the computer merely spits out the stored list of RPO codes. As it does so, it then interprets each one using the current options information. Back when your Jeep was built, each code referred to a particular option or item. Later, Chrysler re-used some of the codes to designate newer or different options. So now when your list is generated, these old codes are given the newer descriptions.
As an example, look at your code XCYS ("Delete Remote Start System"). As you know, your 1998 Wrangler never had any standard-equipment remote start system to be deleted. Back when it was built, that code referred to some other piece of equipment--specifically, the upgraded OBD-II connector. (BTW: part of the confusion is because most option codes were traditionally expressed in 3-character format. Back in the late 90s, though, Chrysler decided to upgrade to 4-character codes for just about everything... typically by simply throwing a dummy extra character onto the end of the same old 3-character code. This has caused more confusion than clarity, IMO.)”
