RTF_CLONING vs RTF_PRCLONING

[Vincent Jardin]

I do not understand the purpose of the flag PRCLONING. What is it for ?

man rtalloc:
 RTF_PRCLONING routes are assumed to be managed
 by the protocol family and no resolution requests are made, but all
 routes generated by the cloning process retain a reference to the route
 from which they were generated.

I agree, then... Isn't it already the purpose of RTF_CLONING ?
When should RTF_PRCLONIG be set ?

Thanks,
  Vincent