This Natural profile parameter disables modifications on the Natural system files FNAT, FUSER, FDIC, and FSEC.

Possible settings	ON	No data can be written to, modified on or deleted from the system files. Natural issues an error message instead of performing any action that would modify any of these system files.
	OFF	Data can be written to, modified on and deleted from the system files.
Default setting	OFF
Dynamic specification	yes
Specification within session	no

Notes:

1. If your system files are specified as read-only (ROSY=ON), the Natural utilities/functions Recording and NATPAGE cannot be used, because they write data to the Natural system files FNAT and/or FUSER.
2. Therefore, it is recommended that you allocate and use a so-called scratch-pad file to hold these temporary data. The scratch-pad file is optional and must be defined as recoverable by using the macro NTLFILE or the profile parameter LFILE. The above functions then will write their data to this file rather than to the system files FNAT and/or FUSER.
3. With ROSY=OFF, a scratch-pad file should also be defined if you use the Recording and NATPAGE functions with database transaction logic, as that might lead to unpredictable results with FNAT/FUSER.
4. If a system file is specified as read-only (RO Option) in the corresponding profile parameter FNAT, FUSER or FSEC, it is not possible to override this setting by setting ROSY=OFF, in order to enable modifications or updates on the affected write-protected system file.