If the environment being initialized is to be an XPLINK environment
then the first program in the PreInit table must be an XPLINK module.
If there is no entry in the PreInit table or if the first module
is a non-XPLINK program, a non-XPLINK environment will be initialized.
It is possible to change the environment from a non-XPLINK to an XPLINK environment
when using (call_main). For more information, see (call_main) — invocation for main routine.