static int selinux_enabled = 0;
The value of variable “selinux_enabled” is
constant 0 of integer type which is not allowed to change.
value of selinux_enabled is constant 0 is Proposition p.
variable selinux_enabled is of type integer is Proposition q .
value of selinux_enabled is not allowed to change is Proposition r.
http://selinuxproject.org/page/Main_Page
http://en.wikipedia.org/wiki/Security-Enhanced_Linux