system:open-url preserved on delivery ?

Hopefully a quick question for anyone who knows:

Is the Lispworks function  system:open-url   kept in the deliverable 
when using delivery levels 4 or 5?

I'm guessing it is not, though I haven't tested enough to verify 
this.  Assuming it is not, which of the delivery keywords would be 
used to preserve it?

Thanks,

Chris