Meaning of "restart" in *.ops files?

[Jeff Clites]

What does "restart" mean in op files, as in "restart ADDRESS(resume);"? 
Also, why does the find_global op use it? I couldn't find it explained 
anywhere.

Also, on a vaguely related topic, in "Parrot_jit_cpcf_op", what does 
"cpcf" stand for?

JEff