$SB_RESTARTFLAG$ behavior?

Have searched the forum for info on the $SB_RESTARTFLAG$, but the few instances I've found didn't help, so posting this.

The SB7 Reference Manual shows the following example on how to inhibit a reboot/restart of the system:

Examples

! Disable reboot/restart at the end of the installation?
Set Installer Flag $SB_RESTARTFLAG$ to "0"

The Common Definitions.sbi that is "included" at the beginning of the script does define the $SB_RESTARTFLAG$ constant in it (checked to make sure). However, when I enter the code from the example at the end of the script (as is suggested), I always receive the error:

error GEN1007: Reference to constant $SB_RESTARTFLAG$ has not been previously defined.

I've poured through the reference manual and the forum for a good 2 hours trying to find what I've missed, but haven't had any luck? Can anyone offer what obvious bit of information am I missing that's causing the error?