There are some setup strings for DOS and WinOS/2 sessions documented in the OS/2 WARP 4 Online help that make their way only into the online help.
A maybe incomplete list of these is :
According to some information exchanged on the Internet, these are new DOS settings that were written for "OS/2 for the PowerPC" version. But they were never added to the Intel version of OS/2 (and probably never will be). Even though you can see the information in the online documentation, you won't find the settings in the settings notebook.
(WARP 4 only!, Source: Team OS/2 WEB pages)